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Jonathan Jurejko
BBC Sport tennis news reporter
The frenzied scene which greeted Jannik Sinner when he arrived at the ATP Finals is an indication of how eventful his season has been.
The Italian world number one, mobbed by home fans and photographers in Turin earlier this week, has been the dominant player in the men's game this year - and the central figure in an ongoing doping controversy.
Sinner is back on home turf looking to cap a successful season with a first triumph at the season-ending Finals, where eight singles players and eight doubles teams do battle.
The Australian and US Open champion has been drawn in a group alongside Russia's Daniil Medvedev, American Taylor Fritz and Australian debutant Alex de Minaur.
Spain's Carlos Alcaraz, who won the French Open and Wimbledon this year, faces Germany's Alexander Zverev, Norway's Casper Ruud and Russia's Andrey Rublev.
Serbia's Novak Djokovic qualified as the sixth-best player but pulled out of the event, which he has won a record seven times.
In the doubles, Britain's Henry Patten makes his tournament debut. The 28-year-old teamed up with Finland's Harri Heliovaara in April, winning the Wimbledon title and finishing as the seventh-best team this season.
The eight-day tournament starts on Sunday, culminating with the final on 17 November.
Meet the singles contenders
Jannik Sinner, 23, Italy
Seed: 1
Best ATP Finals performance: Runner-up (2023)
2024 titles: 7 (Australian Open, Rotterdam, Miami, Halle, Cincinnati, US Open, Shanghai)
2024 win-loss: 65-6
Sinner, whose unassuming personality contrasts with his ferocious hitting, landed his first major title in Melbourne as he lost just once going into April. Shock news arrived in August that he had failed two doping tests but he was allowed to continue playing as an independent panel accepted there was "no fault or negligence" on his part. He went on to win the US Open and has been beaten only once in his past 23 matches.
Daniil Medvedev, 28, Russia
Seed: 4
Best ATP Finals performance: Winner (2020)
2024 titles: 0
2024 win-loss: 45-19
While far from his best season, Medvedev continues to challenge when it comes to the biggest prizes. Beaten in the Australian Open final, he also reached the Wimbledon semi-finals and US Open quarter-finals. His consistency, despite not winning a title this year, was enough to reach the Finals for a sixth straight season.
Taylor Fritz, 27, United States
Seed: 5
Best ATP Finals performance: Semi-finals (2022)
2024 titles: 2 (Delray Beach, Eastbourne)
2024 win-loss: 49-21
What has stood out about Fritz's season is the high level he has produced across all surfaces. He has contested ATP finals on hard, grass and clay courts, including his first Grand Slam final at the US Open.
Alex de Minaur, 25, Australia
Seed: 7
Best ATP Finals performance: Debut
2024 titles: 2 (Acapulco, 's-Hertogenbosch)
2024 win-loss: 47-16
De Minaur's dedication to his craft has reaped even greater rewards this year. Two tour titles, plus three consecutive Grand Slam quarter-final appearances at the French Open, Wimbledon and US Open, have led to a year-end top-10 finish for the first time.
Alexander Zverev, 27, Germany
Seed: 2
Best ATP Finals performance: Champion (2018, 2021)
2024 titles: 2 (Rome, Paris)
2024 win-loss: 66-20
Alongside Djokovic, Zverev is the only multiple ATP Finals champion still playing. A third triumph would bring a positive end to another year without an elusive Grand Slam title. The closest he came was reaching the French Open final, doing so as a court case relating to domestic violence allegations - now discontinued - hung over him.
Carlos Alcaraz, 21, Spain
Seed: 3
Best ATP Finals performance: Semi-finals (2023)
2024 titles: 4 (Indian Wells, French Open, Wimbledon, Beijing)
2024 win-loss: 52-11
This time last year, Alcaraz was burned out. The physical and mental fatigue of a long season took its toll, although he still reached the last four at the Finals. This year has brought two Grand Slam triumphs and two Masters victories, and he hopes smarter scheduling will lead to another high-profile title.
Casper Ruud, 25, Norway
Seed: 6
Best ATP Finals performance: Runner-up (2022)
2024 titles: 2 (Barcelona, Geneva)
2024 win-loss: 49-22
After failing to qualify last year, Ruud's return is based on a front-loaded season. A strong clay-court swing led to the Barcelona and Geneva titles, plus a run to the Roland Garros semi-finals. A debilitating illness has meant the second half of the year has been a struggle, but he secured his spot when Djokovic pulled out.
Andrey Rublev, 27, Russia
Seed: 8
Best ATP Finals performance: Semi-finals (2022)
2024 titles: 2 (Hong Kong, Madrid)
2024 win-loss: 42-23
Like De Minaur and Ruud, Rublev had the potential challenge of a three-way battle for the final two spots taken away by Djokovic's decision. Winning the Masters title in Madrid has been the clear highlight in a season where his frustrations have been demonstrated by a series of angry outbursts.
Who do you think will win - vote
How does the tournament work?
The Finals are contested by the eight singles players and eight doubles teams who have accumulated the most ranking points over the season.
The qualifiers are seeded by points accrued and drawn into the two groups.
A round-robin format decides who qualifies for the semi-finals, which take place on Saturday, 16 November.
The winners contest the finals on Sunday, 17 November.
In the group stage, there are daily afternoon and evening sessions which each feature one doubles match before one singles match.
Play starts at 10:30 GMT in the day and 17:00 GMT at night, with daily reports on the BBC Sport website and app.