Novak Djokovic produced a masterclass against Argentina's Diego Schwartzman on Monday as he started on his campaign for a record-equalling sixth title at the ATP Finals in London.
The world No 1 wobbled at the start of the match against the diminutive eighth seed, making his debut at the elite eight-man event but recovered to win 6-3, 6-2.
Djokovic, who has already sealed the year-end No 1 spot – that also for a record-equalling sixth time – is aiming to match Roger Federer, who holds the record of ATP Finals wins.
The Serbian, 33, has enjoyed another sparkling season despite the coronavirus interruption, winning four titles including the Australian Open.
"The second set I started swinging through the ball more and with less hesitation," Djokovic said. "I was very pleased with the way I played.
"It was close I think until I broke at 4-3. It was tough for Diego, first match in the arena he maybe wasn't playing his best in the closing moments of the first set.
Schwartzman started impressively, breaking Djokovic in the third game but double-faulted in the following game to gift his opponent two break points and the Serbian levelled at 2-2.
Djokovic broke again in the eighth game and clinched the set. With no fans in the 18,000 arena to rally to the Argentine's underdog cause, world No 9 Schwartzman never looked capable of turning the match into a contest.
Djokovic was immediately in the driving seat in set two, breaking the diminutive Argentine to take an iron grip on the match.
He repeated the feat in the fifth game when Schwartzman went wide with a forehand and although the Argentine added a bit of respectability to the scoreline with a hold, it just delayed the inevitable.
In the evening match in Group Tokyo 1970, Daniil Medvedev takes on 2018 champion Alexander Zverev in a rematch of last week's Paris Masters final, when Medvedev came out on top.
World No 2 Rafael Nadal, chasing his first ATP Finals crown, won his opening match in Group London 2020 on Sunday, along with US Open champion Dominic Thiem.
The O2 Arena is hosting the ATP Finals for the 12th and final season before the year-end championships moves to Turin next year.