Novak Djokovic will end the year as world number one for a record eighth time after he beat Holger Rune at the ATP Finals in Turin, Italy.
The 24-time Grand Slam champion overcame the Dane 7-6 (7-4) 6-7 (1-7) 6-3 in his opening Green Group match at the season-ending event on Sunday.
Victory for Djokovic extends his winning run to 19 consecutive matches.
The 36-year-old Serb won three Slams in 2023 to become the all-time record-holder of major titles.
Rune, 20, who is making his debut at the event, claimed the first break to lead 3-2 before Djokovic hit back and went on to win the opening set tie-break.
Rune reacted well and continued his streak of winning a set in every previous meeting with Djokovic to level the game in a second set tie-break.
Djokovic broke immediately in the deciding set, but Rune was able to respond before the Serb broke for a second time and ended the youngster’s challenge.
Djokovic is on course for a seventh ATP Finals title, which would make him the record-holder, having equalled Roger Federer on six last year.
Djokovic told Prime Video: “It took everything. I saw in the first game when he fired shots from the baseline, I knew it was going to be a tough night for me. I thought he played great. I played great in some moments.
“Overall, a win is a win. It was a very emotional win and a tough win knowing the significance of tonight’s match. After a really terrible second-set tie-break, I think I played a really solid third set.”
Earlier on Sunday, home favourite and fourth seed Jannik Sinner beat Stefanos Tsitsipas in straight sets.
Sinner put in a dominant performance to win 6-4 6-4, sealing victory with his ninth ace.
Greece’s Tsitsipas, the 2019 champion, struggled to match his opponent and did not force a single break point.
“I was excited to step on court and opening the Finals is really, really special,” Sinner, 22, said.
“I knew it was going to be very tough but I think I handled the situation well. I tried to stay aggressive and I am very happy with the performance.
“I am happy to start off with a win and hopefully I can continue with this intensity.”
It is the first time Sinner has qualified for the ATP Finals on merit, having replaced Matteo Berrettini in the line-up for the 2021 edition after his compatriot withdrew through injury.
This year he reached his first Grand Slam semi-final at Wimbledon and won his maiden Masters 1000 title at the Canadian Open in August.
He came into his tie with Tsitsipas having trailed the sixth seed 5-2 in their head-to-head but looked relaxed on court as he saw out the win in one hour 25 minutes.
The ATP Finals features eight of the year’s best men’s players split into two groups of four, with the top two qualifying for the semi-finals.
