The PGA Tour is to introduce blood testing next season and will align its list of prohibited substances with that of the World Anti-Doping Agency.
The Tour will still use urine testing to combat anti-doping but the added use of blood testing will detect substances such as human growth hormone.
Commissioner Jay Monahan said the move would “better substantiate the integrity of golf as a clean sport”.
Suspensions due to recreational drug use will also now be reported.
Currently, misdemeanours related to recreational drugs are kept confidential but this will no longer be the case as part of widespread changes in policy for the 2017-18 season, starting later this year.
The PGA Tour provides the week-to-week competitions for many of the world’s top golfers who base themselves in the US, while the European Tour does so in Europe.
It has operated its own anti-doping programme since 2008 and consulted with both Wada and US Anti-Doping in putting it together.
But its banned list differed to the Wada code in three categories, relating to asthma medications, allergy and anti-inflammatory medications.
The International Olympic Committee urged the PGA Tour to adopt fully Wada’s code before the sport’s return to the Olympic Games in 2016, where players were subject to blood testing.
So the USGA erred on the side of caution to ensure their prime event did not suffer any further loss of credibility.
With strong winds sweeping the course on the final day they, quite rightly, slowed the greens to ensure they remained playable.
All of these factors and especially the pristine putting surfaces ensured low scoring. Koepka’s 16-under-par tally equalled Rory McIlroy’s 2011 record at a rain-soaked Congressional.
But on that occasion the Northern Irishman won by eight strokes, no one else came close to taming the Maryland venue in such a manner. Twenty players broke par six years ago; this time the top 31 were in red figures.
Of course, the fact that Erin Hills was rated par-72 skews the figures (Congressional was par-71) but the scoring on a 7,800-yard course emphatically shows that distance is no longer a barrier in the modern professional game.
On the final tee last Sunday, Koepka knew he was on the threshold of his maiden major title.
With a subsiding wind at his back he tackled the 681-yard par 5 with a three-wood and promptly dispatched it 379 yards.
In that last round, fifty of the 68 players to make the cut averaged more than 300 yards off the tee.
Professional golfers are, for the most part, gym-honed athletes trained to make the most of the powerful and generous sweet-spots that are the hallmark of modern golf clubs.
This takes nothing away from the undoubted skill they possess in channelling that power. Koepka is the perfect example because it was not just his length from the tee but his accuracy that provided the platform for his win.
“I drove the ball really well this week, so that really helps,” the champion noted.
“Obviously the fairways were a little bit wider and to have that where some of the misses typically would be in a bunker or deep rough, like a typical US Open.”
The Floridian champion averaged 322 yards with his drives, the seventh longest, but hit 88 percent of fairways (fourth) throughout the week. That is a major-winning combination on a course characterised by length both in terms of yardage and rough.
Koepka made the most of the generous fairway widths as he became the seventh successive first-time major champion.
This run stretches back to Zach Johnson’s Open triumph at St Andrews in 2015. The American winner at the Old Course is a rarity in not being known for his prowess from the tee.
Subsequent major winners; Jason Day (PGA), Danny Willett (Masters), Dustin Johnson (US Open), Henrik Stenson (Open), Jimmy Walker (PGA) and Sergio Garcia (Masters) are all powerful, long hitters.
Kopeka continues the trend and now pundits such as the Golf Channel’s Brandel Chamblee are advocating courses that break the 8,000 yard barrier.
It is an ill-affordable nightmare scenario. Layouts would need more land, more resources for maintenance and more time to play.
The emphasis is all on power and the subtlety of shot making and shaping is being lost.
Amazingly, the authorities insist the golf ball is not travelling any further. They claim to have put the brakes on technology but the evidence of last week and most other professional tournaments tells a different story.
Something needs to be done to rein back the ball to ensure courses remain relevant and the sport becomes more nuanced.
In the mid-90s, tennis realised it had a problem because fans were being put off because there were too few rallies at tournaments such as Wimbledon.
What did they do? They slowed down the ball and transformed the sport.
It was their ball and they had control. In golf it does not work that way because manufacturers hold sway.
The time is long overdue for the rules-makers to assume proper control. The R and A and USGA have to come up with a blueprint for a tournament ball appropriate to whichever course is being used that week.
Dictate the specifications and limits to the manufacturers and let them come up with the best ball they can.
The emphasis would shift from raw length to feel and playability while we amateurs could still use balls that give us the sort of distance that makes the game more enjoyable for us.
It might be possible to build monster courses such as Erin Hills in the wide open spaces of Wisconsin to accommodate the power of the modern game but it is inconceivable for golf’s future to be based on such exceptional sites.
American Brooks Koepka equalled the US Open’s lowest winning score of 16 under to claim his first major at Erin Hills.
Koepka had three successive birdies from the 14th to match the total set by Rory McIlroy when he won in 2011 on a par-71 layout compared to this par 72.
His five-under 67 was only bettered by Japan’s Hideki Matsuyama who posted 66 to tie for second on 12 under with overnight leader Brian Harman (72).
England’s Tommy Fleetwood, shot a level-par 72 to end fourth on 11 under.
The 26-year-old from Southport, playing in just his second US Open, was unable to keep pace with playing partner Koepka on the front nine.
The pair started Sunday’s final round one off the lead but Koepka holed three birdies in his first eight holes, while Fleetwood followed a birdie on the second with three bogeys in his next six holes for a five-shot swing.
Fleetwood, ranked 33rd in the world, steadied his round with a birdie on the ninth and returned to 11 under by picking up another shot on the par-five 14th.
-12 B Harman (US); -11 J Thomas (US), B Koepka (US), T Fleetwood (Eng); -10 R Fowler (US); -9 K Si-woo (Kor)
Selected: -8 P Reed (US); -6 H Matsuyama (Jpn); -4 E Pepperell (Eng), S Garcia (Spa) C Champ* ((US), P Casey (Eng); -3 M Fitzpatrick (Eng); -1 M Laird (Sco), A Johnston (Eng); +3 L Westwood (Eng); +4 J Spieth (US); +5 E Els (SA)
* denotes amateur
Tommy Fleetwood has been backed to win the US Open by coach Norman Marshall, who first taught him as a six-year-old.
England’s Fleetwood, who has never won a major, is one shot off the lead going into the final round on Sunday.
“Knowing Tommy as I know him and seeing what he has done in the past, every time he has got within a sniff of winning a big tournament, he’s gone for it 100%,” said Marshall.
“There’s no backing down in Tommy and that’s what the exciting thing is.”
England’s Tommy Fleetwood is one shot off Brian Harman’s lead going into Sunday’s final round of the US Open.
Fleetwood shot a four-under-par 68 to keep pace with fellow overnight leader Brooks Koepka at Erin Hills, while Harman carded a 67 to lead on 12 under.
Paul Casey, who also started on seven under, fell away with a three-over 75.
Justin Thomas is tied for second after becoming the first man to shoot a nine-under-par round at the US Open and the fifth 63 in its 117-year history.
Thomas’ record round
There had been four other 63s in US Open history before this week. Jonny Miller hit the first on the par-71 Oakmont in 1973, while Jack Nicklaus and Tom Weiskopf’s efforts came on the par-70 Baltusrol in 1980.
Fiji’s Vijay Singh also recorded a seven-under 63, at Olympia Fields in 2003.
The US Open tournament organisers have historically prided themselves on trying to make the winning score as close to level par as possible.
However, heavy overnight rain dumped an inch of water on the course and that undoubtedly helped low scoring with players able to take advantage of receptive greens and attack the holes.
Thomas opened his round with two birdies before dropping a shot on the fourth. Four more birdies followed on the front nine before another bogey on the 10th looked to have put paid to his chances of breaking Miller’s 44-year-old record.
But after three birdies in six holes, he eagled the 667-yard par-five 18th, hitting his second shot to eight feet from 300 yards and rolling in the downhill putt.
Fleetwood’s fortunes falter at last
Southport’s Fleetwood, who finished tied for 27th on his only other US Open appearance in 2015, appeared to be heading towards his second bogey-free round of the tournament after laying up with his second shot on the par-five 18th.
However, he left his chip to the green short and then putted through the green and off it with his fourth shot. A deft chip to three feet allowed him to escape with a bogey.
Patrick Reed’s seven-under 65 featured eight birdies and one bogey as he improved to eight under.
He said he felt like he “hit the ball better” in Friday’s second round, despite taking 10 fewer strokes on Saturday.
Reed explained: “I was really seeing the lines and had the speed. And most of my birdie putts were uphill and I could attack. On Friday it was the opposite.”
Russell Henley (67), Charley Hoffman (68) and Brandt Snedeker (69) are all in a group three off the lead on eight under.
Rickie Fowler had a run of three successive birdies from the 14th as the leader from the first round, shot a four-under 68 to get to 10 under.
Former winners falter
However, not all Americans fared well. Jordan Spieth, the 2015 champion, started the day level par and was still on that mark after a couple of birdies cancelled out two bogeys in the opening 11 holes.
Two more bogeys followed though and a double-bogey on the par-five 18th saw him finish four-over after a 76.
“It’s been an off-week for me with the putting,” said the former world number one. “I’ve been striking the ball well.
“It’s just been trying to figure it out on and around the greens. And I feel like once the can gets open, I’ll start pouring them in.”
Germany’s Martin Kaymer, winner in 2014, took 41 shots to complete the front nine and although he picked up two birdies on the back nine, his three-over 75 saw him drop back to level par.
And two-time winner Ernie Els, who was two under after round one, dropped five shots in his opening six holes on Saturday. The South African rallied with an eagle two on the par-four 15th but had a triple-bogey seven on the 17th to drop to five over after a 79.
The rest of the Brits
England’s Eddie Pepperell, 26, had five birdies and two bogeys in his three-under-par 69 to get to four under and remain in with a chance.
After dropping three shots in his opening six holes, Matt Fitzpatrick holed five birdies in eight holes to post a two-under 70 to climb to three under.
Fellow Englishman Andrew Johnston mixed three birdies with four bogeys as he slipped back to one under with a 73.
And Scotland’s Martin Laird is putting together a solid tournament with nine birdies and nine bogeys in his opening three rounds.
However, it looks like Lee Westwood’s wait to win a major will go on to The Open in July. The Englishman was three under after round one, but he followed Friday’s 75 with another 75 today to drop to three over.
-7 P Casey (Eng), T Fleetwood (Eng), B Harman (US), B Koepka (US); -6 J Lovemark (US), R Fowler (US), JB Holmes (US)
Selected: -5 S Kim (Kor), H Matsuyama (Jpn), C Champ (US)*; –3 S Garcia (Spa), M Kaymer (Ger); -2 A Johnston (Eng); -1 E Pepperell (Eng), M Fitzpatrick (Eng), M Laird (Sco); Level L Westwood (Eng), J Spieth (US); +1 S Lowry (Ire); +2 R Ramsey (Sco), J Rose (Eng), R Fisher (Eng); +3 C Wood (Eng), A Scott (Aus); +4 D Johnson (US); +5 R McIlroy (NI), J Rahm (Spa), G McDowell (NI), R Knox (Sco); +10 J Day (Aus)
* denotes amateur
English duo Paul Casey and Tommy Fleetwood are in a four-way tie for the lead after two rounds of the US Open.
Casey posted a one-under 71 to move to seven under, while Fleetwood and Americans Brian Harman and Brooks Koepka signed for 70s at Erin Hills.
For the first time since world rankings began in 1986, the top world’s top three have missed the cut at a major.
Defending champion Dustin Johnson (+4), Rory McIlory (+5) and Jason Day (+10) finished above the one-over-par cut.
Overnight leader Rickie Fowler was going on serenely at nine under until three successive bogeys from the 11th saw him drop back into the pack.
The American recovered to post five pars and salvage a one-over 73 to sit one off the lead, with Jamie Lovemark and JB Holmes who both shot 69s.
Big names miss cut
World number one Johnson, who recorded his first major victory in this tournament at Oakmont a year ago, flirted with the projected cut mark all day. He opened on three over but birdied the first two holes.
However, he was unable to build on that momentum and was still one over par after a birdie on the 12th.
Bogeys on the 13th and 14th dropped him back to three over and a further shot went on the 17th.
Northern Ireland’s McIlroy, who was playing his first tournament after a month out injured and only his seventh of the year, signed for a one-under 71, after knocking in four birdies in his final six holes, but the damage was done by his six-over 78 in round one.
“I showed up for the last six holes at least,” joked world number two McIlroy, who misses his second successive US Open cut.
“I saw some positives on the back nine to take into next week and, even though this is disappointing, the last two rounds will serve me well in this busy summer.”
World number three Day followed his opening 79 with a 75 to limp out on 10 over.
“It’s been the best preparation going into a major in my career,” said the Australian, who conceded: “I was in the hay too much over the last couple of days.”
Casey keeps composure
After opening with a six-under 66, Casey was one off the overnight lead as he went out among the early starters on Friday.
He started on the 10th, birdied the 11th but bogeyed the 12th before coming unstuck on the 14th. He was within 100 yards of the green after two shots but hit his third in to deep rough and took five from there to post a triple-bogey eight.
A bogey on 15 dropped him to two under but a run of five birdies followed to catapult him to the top of the leaderboard.
“It’s very difficult to get get through a major championship, let alone a US Open without a blemish on your card,” the 39-year-old told BBC Sport.
“I made a complete mess on the 14th. It’s how you react to it. I tried to take my medicine and then messed up the next hole. But I got on a wonderful birdie streak.
“It was important to do that. I didn’t change the game plan. John, my caddy and I kept communication great. We talked it out and got back to hitting the fairways and doing the basics and that led to some birdies on the front nine. I’m really, really happy with it.”
Fleetwood finds the rhythm
Southport’s Fleetwood said it would be “nice to sit down to dinner knowing you’re top of the US Open leaderboard” after overcoming “a ropey start” to his second round.
The 26-year-old bogeyed the first hole but had three birdies and 12 pars before dropping his next shot on the 17th. However, he finished his round well with a birdie at the par-five 18th.
“I was enjoying it,” he told BBC Sport. “I had a couple of bad drives early in the round and I had to focus on my rhythm and slow things down but as I got into the round it became more natural and I hit a lot of good shots and felt comfortable out there.”
On a charge
Japan’s Hideki Matsuyama posted the joint lowest round of the day, a seven-under-par 65 to move into a tie for eighth on five under.
The world number four knocked in six birdies on the front nine and one more on the back nine in a bogey-free round.
However he missed an opportunity to tie Jonny Miller’s US Open single round record of eight under when his nine-foot birdie attempt at the last stayed up.
Matsuyama is joined on five under by, among others, amateur Cameron Champ who had three-under-par 69.
American Chez Reavie also leapt up the leaderboard with a 65 to get to four under – he had eight birdies and one bogey – and missed a 25-foot putt to tie Miller’s 1973 record on the short ninth.
Garcia leads European challenge
Masters champion Sergio Garcia kept his challenge on track with a solid one-under-par 71. He signed for three birdies and two bogeys to finish three under, alongside 2014 US Open winner Martin Kaymer (69) and Austria’s Bernd Wiesberger (72).
The best (and worst) of the Brits
Olympic champion Justin Rose is another who will be heading home early after carding a two-over 74. The Englishman, champion in 2013, birdied the par-five seventh to move to level par but bogeyed the next two to finish the tournament on two over.
In fact, of the 14 Englishmen, three Scots, two Northern Irishmen and one Welshman who started on Thursday, only seven will play the weekend.
Andrew Johnston is five off the lead after a 73, while fellow Englishmen Eddie Pepperell (71) and Matt Fitzpatrick (73), and Scotland’s Martin Laird (71) are in a group on one under.
Lee Westwood had a three-over 75 to drop back to level par.
Among those missing the cut were Bradley Dredge of Wales and England’s Chris Wood on three over while 2010 champion Graeme McDowell closed on five over.
England’s 2016 Masters champion Danny Willett withdrew before the start of his second round with a back injury.