Jannik Sinner moved to within touching distance of an ATP Finals last four spot on Tuesday with his first career defeat of Novak Djokovic.

The Italian crowd darling had the full  support of home fans in Turin during a 7-5, 6-7 (5), 7-6 (2)  thriller in which the Serb fulfilled the role of cartoon villain.

World No. 1 Djokovic drew repeated jeers for arguing with the chair umpire and repeatedly questioning electronic line calls and lets.

ATP No. 4 Sinner kept his focus on the prize as he won in just over three hours in another post-midnight conclusion at the Pala Alpitour.

He finished off the upset after losing three times to the 36-year-old – including twice at Wimbledon.

“This means a lot to me,” Sinner said. “When you beat the world No. 1 with 24 Grand Slam titles, it’s one of my best matches.

“I managed to win a very tactical match, so I’m very happy.

Sinner lifted the first set with a single break of his opponent but lost his way to drop the second-set tiebreaker.

But the Italian from German-speaking Alto Adige came alive in the third set decider, running off a 5-0 lead and triumphing with an overhead smash on his second match point.

He now owns two wins in group play and is on the verge of booking the weekend semis here.

“I’m feeling more confident in the tight moments,” Sinner said. “I was brave in the third set tiebreak.

“We were both serving really well. There were not a lot of long rallies but it was a high-level match.”

Sinner added: “I managed to play the important points better. I was tense after 

losing the second set but the fans helped me through.

“It was a roller-coaster but in the end I won.”

Djokovic still has a chance to emerge from the group stage as he seeks a seventh year-end trophy after losing to Sinner in their first match on a hardcourt.

Sinner could become the first Italian to ever reach the semis finals in the tournament’s 54-year history.

Main photo:- Jannik Sinner celebrates as he beats Novak Djokovic for the first time – by ATPTour.com