Jannik Sinner earned one of his best career wins and he did it in style. Sinner downed Novak Djokovic in a classic at the ATP Finals 7-5, 6-7(5), 7-6(2) in just over three rounds.

“It’s part of the process. I feel that I’m a little bit more confident in certain moments in a match,” Sinner told the ATP. “I think I was really brave and intelligent in important moments, especially the third set. I felt like we were both serving really well so there were not so many exchanges, but when the exchanges were played we both played really well.

“That was a really high-level match.”

Sinner had lost to Djokovic all three previous meetings but Sinner struck first taking the opener capitalizing on Djokovic’s weaker second serve.

Djokovic trailed in the second set breaker before erupting winning five of the last seven points as Sinner let down.

But the Italian, who had played so well all match, raised her level even higher in the final breaker, dominating Djokovic.

Djokovic had won his last 19 matches coming in and finished +16 in winners/errors, but came up just short.

“I think the main difference is that in the important points, he was going for it, he was more courageous,” Djokovic said. “He deserved to win because in important moments I wasn’t aggressive enough, I wasn’t decisive enough. I gave him the opportunity to take the control over the points. At 5-all in third set, 15-30, second serve, I was in the rally and should have stepped in and didn’t, and he did.

“You have to just congratulate him. He just played a fantastic match. That’s what I told him at the net. I think in the most important moments, he played his best game and he absolutely deserved to win.”

Djokovic will now face Hubert Hurkacz on Thursday with a spot in the semifinals at stake.

Hurkacz replaced Stefanos Tsitsipas had to retire down 2-1 to Holger Rune at the start of their round robin match. Tsitsipas cited a bad back.

“For me, it’s important to be fit and feel good with my back. The pain was very big,” Tsitsipas said. “I’ve gone through pain during matches in the past, and I endured pain, but this was clearly too much to handle. I had to take the difficult decision to do what I did.

“I felt it at the second game of the match. I actually felt it in the warm-up with my serve. Warming up on my serve, I felt very irritated and lots of pain hitting me on my back. I kind of knew at that time that I might not be able to go all the way.”

Rune will now face Sinner on Thursday. Rune will have to win to have a chance to reach the semifinals.

Tomorrow, Daniil Medvedev and Alexander Zverev resume their rivalry. Medvedev leads 10-7 in this battle of former ATP Finals winners. They will meet for a sixth time this year with the Russian taking four of them. The winner will all but lock in a semifinal berth.

Also, Carlos Alcaraz returns to face Andrey Rublev.