Stanislas Wawrinka claimed a three-set victory over Tomas Berdych in the opening match of the ATP World Tour Finals at the O2 Arena in London.
Impressive serving helped the Swiss take the first set, but a resurgent Berdych capitalised on Wawrinka's errors in the second-set tie-break.
However, Wawrinka turned on the style in the decider for a 6-3 6-7 (0-7) 6-3 victory in two hours and 25 minutes.
Juan Martin Del Potro plays Richard Gasquet later on Monday.
Victory gives Wawrinka - who had not before qualified for the World Tour Finals - an early advantage in Group A, which also includes Rafael Nadal and David Ferrer, who play on Tuesday.
"It was a dream come true to win on my debut here," the world number eight told BBC Sport.
"I have watched many times on TV and today I was here on court. I'm happy to get the win. It's never easy on your first time here but I'm happy with way I played today.
"It's only one match - I take it match after match. I know how I can play and now I'll get ready for the next one."
Wawrinka, who beat Andy Murray en route to the semi-finals of the US Open in September, looked immediately at home on his debut at the O2 Arena, dropping only one point in his opening three service games.
He forced a break in the sixth game of the match and, after a wobble when serving for the set, eventually grasped a fifth opportunity.
Berdych, the world number six, improved in the second set but still could not find a way past Wawrinka, the Czech wasting four break points.
In the tie-break, though, rare Wawrinka errors opened the door for Berdych and the 2010 Wimbledon finalist raced through 7-0 to send the contest into a third set.
But Wawrinka was not to be denied and, after a Berdych double fault gifted away a break point, a further mistake gave the Swiss the advantage.
Now oozing confidence, best demonstrated by the deftest of drop shots from the baseline, Wawrinka eased through the decider and served out for victory.
"Losing is not a good start but there are still two other matches to go," said Berdych. "It was really about the small chances - Stan was better in executing the chances.
"He had four break points and made two; I had five, made zero. I think that's been a really big difference today."
The Del Potro-Gasquet contest is in Group B, where they are joined by Novak Djokovic and Roger Federer.