Roger Federer and Alexander Zverev won their Laver Cup doubles match as Team Europe lead Team World 3-1 after day one of the event in Geneva, Switzerland.
Federer and Zverev beat Jack Sock and Denis Shapovalov 6-3 7-5.
Shapovalov also lost to Dominic Thiem while Greece’s Stefanos Tsitsipas beat American Taylor Fritz.
Sock had earlier beaten Fabio Fognini of Italy 6-1 7-6 to secure Team World’s only point of the opening day.
Shapovalov and Sock converted just one of 16 break points, failing to take any of six set points in one game off Zverev’s serve during the crucial second set.
After Zverev held serve to level the set at 5-5, a double fault from Shapovalov in the next game gave the Team Europe pair a crucial break.
Federer served out the next game to secure victory and move further ahead in the all-time Laver Cup standings with 13 points.
Speaking in front of his home crowd, Swiss world number three Federer said: “All of us tennis players travel around the world for 10, 11 months of the year.
“There’s no place like playing at home, so this is a very special night for me.”
Austrian world number five Thiem saved three match points against Canada’s Shapovalov in the opening singles match of the competition before going on to win 6-4 5-7 13-11 courtesy of a super tie-break.
Tsitsipas also needed a super tie-break to overcome fellow tournament debutant Fritz 6-2 1-6 10-7.
That put Europe back in front after American Sock became the first Team World player ever to win an opening-day singles match with victory over Fognini.
Two points per match are on offer on day two of the three-day tournament, with the first team to reach 13 points declared the winner.
The Laver Cup is into its third year but this is the first time the tournament is an officially sanctioned ATP Tour event.
The previous tournaments, in Prague and Chicago, took place on an exhibition basis.
Danny Willett shot a seven-under-par round to share the halfway lead in the BMW PGA Championship at Wentworth.
The Englishman, 31, carded six birdies and an eagle to reach 11 under, the same mark as Spain’s Jon Rahm.
Justin Rose is tied for third on nine under, while Northern Ireland’s Rory McIlroy just made the cut, shooting three under to reach one over overall.
“I didn’t really do much the last couple of weeks and some things start to creep into your game,” said McIlroy.
The 30-year-old, who won the Fed-Ex Cup in August, added: “I’m happy to be here for the weekend. I had to battle hard out there just to be here. I’m proud of myself for hanging in.
“Plus one, obviously the leaders are way up there, but the conditions are going to be tricky.
“The course is getting firm. If I can shoot seven-under tomorrow, get myself to minus six, you never know… I went low on this golf course before, so I feel like I can do that.”
Willett continues fine form
Round two of the European Tour’s flagship event could not be fully completed because of bad light and five players will conclude their round from 0715 BST on Saturday.
Willett’s fine round was further evidence of his return to form having slipped to 462 in the rankings in 2018.
The 2016 Masters champion is now ranked at 58 and his mark of seven under on Friday was only matched by American Billy Horschel, who is seven under overall.
“I’m probably not back to my best,” said Willett, who won the DP World Tour Championship in August.
“I’m still working on the moves and there’s still shots in there that I don’t like.
“As a whole, the body is night and day to where it was and the movements are good. The ability to travel around the world and play golf now is back there and I’m just in a much better place with everything, really. Hopefully an exciting weekend to come.”
Rahm eyes legend status
England’s Tommy Fleetwood just made the cut at one over par to remain the only player in the world’s top 50 yet to miss a cut in 2019.
Rose is joined on nine under in third place by Sweden’s Henrik Stenson and South African Christiaan Bezuidenhout.
Rahm, 24, looked like he too would share the mark but he converted an eagle on the last to join Willett, capping a fine recovery given he made bogey on his opening two holes.
“I didn’t lose patience or panic, because I know I have the whole round to go and I have the whole day to make it up,” said Rahm, the world number six.
“There’s a lot of history here and a lot of legends on the walls, so it would be great to join that great list of players.”