Roger Federer started his bid for a seventh ATP Tour Finals title in record-breaking fashion, crushing Janko Tipsarevic 6-3, 6-1 at London's O2 Arena.
Federer's victory took him to 40 match wins in his 11 appearances at the prestigious season-ending event, breaking the previous record of 39 held by Ivan Lendl.
Federer: Djokovic right to seal top spot
World no. 2 Roger Federer explains the current season and what it is like to defend the number one spot.
Spain's David Ferrer extended his winning run to 11 matches with a hard-fought 6-3, 3-6, 6-4 victory over Juan Martin del Potro in the other group B match on Tuesday.
Federer already has a record six titles in this season-ending event after winning the tournament for the past two years and he looks in the mood to complete a hat-trick on the evidence of this emphatic group B victory over the Serbian eighth seed in just one hour and eight minutes on Tuesday.
"I'm very happy I played so well because Janko's a great player," Federer said.
"I've had a great year but I hope it's not over yet.
"It's my third trip to London this year. The other two were pretty good and I hope something similar is going to happen this week."
Since winning Wimbledon for a 17th Grand Slam crown and returning to the top of the world rankings in July, Federer has endured something of a rough ride by his own sky-high standards.
He squandered a chance to win a gold medal in the Olympic singles after being thrashed by Andy Murray in the final and then suffered a shock loss in the US Open quarter-finals against Tomas Berdych.
Federer was also beaten by Juan Martin del Potro in the final of his hometown event in Basel last month and surrendered his No.1 ranking to Novak Djokovic as a result.
But whatever his struggles elsewhere, Federer has always thrived at this season finale and the world No.2 was quickly into his stride against Tipsarevic.
Federer broke in the second game and raced to a 3-0 lead, the first set over in 30 minutes.
Tipsarevic staved off two break points in the third game of the second set, but Federer kept dictating play from the baseline and he finally induced a miscued forehand from the Serb to break for a 2-1 lead before running away with the win.
Ferrer arrived in London in the best form of his life after winning his first Masters event on Sunday.
He had to dig deep to maintain that fine form, as he subdued former US Open champion del Potro in two hours and 16 minutes to secure a victory in his opening group B match at the season-ending tournament.
"I am very happy. It was a top match," Ferrer said. "It was very difficult to play against Juan Martin, but I hope the people enjoyed our tennis.
"I don't know the secret of my good form. It has been the best season of my career. Maybe it's because I didn't have a big injury."