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Roger Federer starts his bid for a 100th career singles title when he plays Kei Nishikori on the opening day of the ATP Finals in London.
The 37-year-old Swiss, aiming for a record-extending seventh title at the season-ending event, meets Japan’s Nishikori in Sunday’s evening session.
Wimbledon finalist Kevin Anderson takes on French Open runner-up Dominic Thiem in the afternoon session.
World number one Novak Djokovic, who is in the other group, plays on Monday.
The 31-year-old Serb opens his campaign against American John Isner in Monday’s evening session, following the afternoon match between Germany’s world number four Alexander Zverev and Croatia’s Marin Cilic.
Jamie Murray is the only Briton competing in the event, seeded fourth with Brazilian Bruno Soares in the doubles.
The pair open the event at 12:00 GMT on Sunday when they face sixth seeds Raven Klaasen and Michael Venus.
BBC Sport will have comprehensive, live coverage of the tournament across television, radio and online – starting with Federer’s opening match, which you can follow on BBC Four, BBC Radio 5 live and the BBC Sport website at 20:00 GMT on Sunday.
Novak Djokovic (Serbia)
World ranking: 1
2018 highlights: Winning Wimbledon and US Open titles, returning to world number one.
2018 highlights: Reaching Wimbledon final after epic semi-final win against Isner, climbing to career-high fifth in the world.
Previous ATP Finals appearances: Debut
What he says: “Reaching the tour finals for the first time was one of my primary goals this year. I feel I’ve been playing great tennis and if I keep going then can have a chance of a successful result.”
Dominic Thiem (Austria)
World ranking: 8
2018 highlights: Reaching first Grand Slam final at the French Open, also finishing runner-up in Madrid.
Previous ATP Finals appearances: 2 (group stage 2016, 2017)
Kei Nishikori (Japan)
World ranking: 9
2018 highlights: Reached US Open semi-finals, runner-up in Monte Carlo Masters.
Previous ATP Finals appearances: 3 semi-finals 2014, 2016)
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For the fourth time in seven years, Rafael Nadal will not be playing.
The French Open champion finished second in the Race to London rankings, but pulled out of the event earlier this week after having surgery on an ankle injury.
World number four Juan Martin del Potro was also forced to withdraw with the right knee injury he sustained in Shanghai last month.
Britain’s Andy Murray and defending champion Grigor Dimitrov are other star names that will be missing.
Murray, who won the event in 2016, remains in the early stages of his comeback following hip surgery, while Bulgaria’s Dimitrov did not qualify after a poor second half of the season.
How does the tournament work?
The finals are the culmination of the ATP season and the singles title is contested by the eight players who have accumulated the most ranking points from 52 tournaments – including the four Grand Slams – over the year.
The eight singles players are seeded in terms of points accrued and split into two groups of four.
The groups are played in a round-robin format over the course of the week, with the top two players in each qualifying for the semi-finals on Saturday, 17 November.
The winners meet in the final on Sunday, 18 November at 18:00 GMT.
Andy Murray says he is physically feeling “a little bit better every day” after returning to the practice courts in preparation for the 2019 season.
Murray, 31, ended his season early to focus on making “big improvements”, having played in six events since returning from hip surgery in June.
The Scot will train in Miami next month before making his competitive return at the Brisbane International in January.
“I’m getting closer,” said the former world number one.
The Briton, now ranked 263rd in the world, has not played since losing to Spain’s Fernando Verdasco in the Shenzhen Open in September.
He has spent “four or five” weeks building his fitness with off-court training in Philadelphia and plans to increase his workload in Florida before flying out to Brisbane.
Murray is expected to play at the Australian Open later in January and has also announced his entry to the Open Sud de France in Montpellier – an ATP Tour 250 event which he has never previously played – in February.
“I going to get to Miami for three or four weeks to train in the hot conditions and spend a lot more time on the court to get ready for the tournament in Brisbane,” said the three-time Grand Slam winner.
“I’m planning to get to Brisbane pretty early, probably a week before the start of the tournament.
“I’ve been practising already for a few days and I’ve still got a couple of months to get myself in the best shape for the start of the tournament.”
The Lawn Tennis Association is facing a loss of about £7.5m for 2018, leaving a “financial black hole” for next year, BBC Sport has learned.
It follows a £4.7m loss in 2017, amid falling revenues and participation.
It is understood regional offices may close to reduce costs, but regional operations will continue.
The LTA says it “has a new vision to open tennis up and grow the sport through making it relevant, accessible, welcoming and enjoyable to anyone”.
A spokesperson for the national governing body continued: “The LTA is now looking at how best to deliver the new vision and where it can have the greatest impact, to meet the needs of fans, players, coaches and venues to play tennis across Britain.”
Regional briefing documents seen by BBC Sport warned the LTA is facing a “financial black hole” because of this year’s anticipated losses, combined with last year’s confirmed £4.7m deficit.
A temporary reduction in revenues from the Wimbledon Championships because of the construction of a roof on Court One, which is due for completion in 2019, has contributed to the financial shortfall.
The documents also state that participation in tennis in Britain has fallen by nearly 10% compared to last year, despite relative successes on the court by leading players, including Kyle Edmund’s run to the Australian Open semi-finals.
The LTA currently has nine regional offices in England, all of which are understood to be set to close to reduce costs, although their activities will continue to operate from a central base and it is thought that the work of county associations will be unaffected.
On 8 October it was announced that much of the work done by the Tennis Foundation charity will be brought back under the LTA’s control, but that integration is being welcomed and provision for disability tennis is set to be enhanced.
The LTA continued: “The work of the Tennis Foundation with disabled people, young people in education and young people in urban and disadvantaged communities is being integrated into the LTA to give it greater scale and reach.”
The Tennis Foundation added: “We are taking advantage of the opportunity to integrate these activities into the LTA in order to achieve real inclusion across our sport.
“The move received the unanimous support of our board and will see our work not only play a key role in supporting the LTA’s new vision to open up tennis and grow the sport in Britain but, crucially, enable it to be delivered with greater scale and greater impact than ever before.
“We are tremendously proud of the achievements of the Tennis Foundation over the last 31 years and the legacy we have created, which the LTA can now take forward and build on as part of a bright future for our sport.”
Russell Fuller, BBC tennis correspondent
The LTA may have reserves of nearly £140m, but will be concerned by a potential loss of about £12m over two years.
This year’s accounts will be compromised by the end of a lucrative nine-year partnership with Aegon. The financial services company acted as both lead partner of British Tennis, and title sponsor of June’s grass court events, until the end of 2017. The sponsorship provided by Fever Tree and Nature Valley in the summer of 2018 was not as extensive.
The LTA is at least assured a healthy long-term income as, under an agreement with The All England Club, it will receive 90% of the profits generated by Wimbledon until 2053.
A fall in revenue from Wimbledon was the principal reason for last year’s financial loss, although safeguarding and IT costs were also a factor.
The outgoing chairman David Gregson said at October’s meeting of the LTA Council that “work had to be done to align certain areas so that reserves were not used in the future”.