Defending champion Stefanos Tsitsipas is back at the ATP Finals, something he considers quite a big achievement in itself.
The top eight players in the rankings qualify for the round-robin event, which wraps up the ATP season.
"Every year I get to experience being back here is thrilling," Tsitsipas told press before the event. "I know it’s not easy to be in this position, and I’ve really worked hard for it.
"It’s like a meeting spot for those that had a good year, just to be back here and celebrate their hard work, their dedication to the sport, and I’m very privileged to be part of it."
The 22-year-old from Greece has built on his 2019 victory with a solid if not spectacular season. That includes reaching the final of Hamburg and the semifinals of Roland Garros back-to-back despite experiencing a leg injury in Rome.
He was also bothered by the injury in successive defeats in Vienna and the Paris Masters, withdrawing from St. Petersburg. But he says the problem has improved.
"I’m happy that I’m able to move more freely and less conscious of my pain. So it’s a positive feedback, and a positive thing to have," the No. 6 said. "This injury kind of like mentally drained me and hasn't made me feel at 100 percent.
"I was in Paris, I stayed for a week to have treatments and the right rehabilitation for my injury.
"Right now, I’m feeling way, way better than I did in Vienna. I hope my leg stays the same and I also hope that I don't have to go through the same things that I have had to go through a few weeks ago."
Tsitsipas will open singles play on Sunday against Dominic Thiem, the man he beat in last year's championship match. Rafael Nadal and Andrey Rublev will square off in the night session.