Novak Djokovic has beaten Stefanos Tsitsipas for the ninth straight time in the players' opening match at the ATP Finals and ended the Greek's hopes of finishing the year as world No.1.
Tsitsipas knew triumphing in Turin and winning every match in the process would have been enough to see him pip the injured Carlos Alcaraz to top spot in the rankings come the end of the season.
But the seventh-seeded Djokovic enjoyed a 6-4 7-6 (7-4) victory on Monday night for a third success of 2022 over the No.2 seed following wins at the Rome Masters, Astana and Paris Masters.
"If I was to play good tennis this week, win all of my matches, for sure I deserve the (number one) spot. It shows good performance, consistency, but it's not really occupying too much of my mind," Tsitsipas said.
"I deeply believe that I can reach that spot one day.
"I'm not really that much in a rush, to be honest. Of course, it would have been better if it happened this week. I am more here for the marathon ... I see the bigger picture, the longer run. I have a lot of opportunities next year to play some good tennis.
"If it comes, I'll be very happy, my country will be very happy, my family will be happy ... If it happens, that's great news. But I shouldn't be obsessing too much about it."
Wimbledon champion Djokovic broke Tsitsipas in the opening game and held from there to close out the first set.
A cross-court backhand passing shot winner that landed on the line helped the Serb move ahead in the second-set tiebreaker, a lead he didn't relinquish.
Tsitsipas won two of his first three career matches against Djokovic but hasn't beaten the 21-time grand slam winner in more than three years.
"It was very important to start off well," Djokovic said.
"I held my serve really well throughout the match. I played a great tiebreak, very solid all the way through."
Earlier, Andrey Rublev recorded a 6-7 (5-7) 6-3 7-6 (9-7) victory over fellow Russian Daniil Medvedev in the other Red Group match.
After his win Rublev wrote "Peace, Peace, Peace, All we need," on a TV camera lens.
Having shaken off the disappointment of squandering several chances to take the opening set, Rublev hit back with 25 winners in the next two and held his nerve in the deciding tiebreak to seal the victory on his fifth match point.
"The final tiebreak, the rallies that we had there were crazy," Rublev said.
"The last rally, we had I don't know, 30 shots ... In the end I was able to win."
On Sunday, Taylor Fritz beat Rafael Nadal and Casper Ruud defeated Feliz Auger-Aliassime, both in straight sets, to get the Green Group underway.
With AP and PA.