Roger Federer got his Masters Cup campaign off to a winning start with a 3-6 6-1 6-1 victory over defending champion David Nalbandian in Shanghai.
Federer hit nine aces on his way to beating Nalbandian
Nalbandian, who beat Federer in the 2005 final, took the opening set with some impressive groundstrokes.
But the Swiss gained control when he changed tactics, bringing Nalbandian into the net and passing him, and wrapped it up in one hour 27 minutes.
Andy Roddick beat Ivan Ljubicic 6-4 6-7 (9-11) 6-1 in the second Red Group tie.
The Gold Group, featuring world number two Rafael Nadal, start on Monday.
606 DEBATE: Give your thoughts on Federer's win in Shanghai
A fiery Roddick at one point lambasted umpire Mohamed Lahyani over a line call, and later saw two match points disappear as he lost the second-set tie-break.
I'm still in the fight, nothing is finished today
But the American just about recovered his poise as Ljubicic's game faded in the decider.
"I avoided the big blow-up today, which I was flirting with. I always feel when I'm playing well I'm able to bring it back when I need to and use it," said Roddick.
"I hear that everybody here was calling this group the 'Group of Death' but the way I see it only two players are dying, so I don't want to be one of them."
Last year, Federer defeated Nalbandian in the first match of the tournament only to lose to the Argentine in a thrilling final.
And Nalbandian appeared to have got the better of the world number one again as Federer made a series of unforced errors in the first set.
I avoided the big blow-up today, which I was flirting with
The Argentine made the decisive break at 4-3 and was gifted the first set point by Federer's only double-fault of the match.
The Swiss world number one answered immediately, breaking Nalbandian in the very first game of the second set and again at 4-1.
Federer was in full swing as he raced to a 4-0 lead in the third while Nalbandian's challenge faded in a rash of errors.
"I had to make him hit some errors but he wasn't doing that at the beginning," the world number one said.
"I tried to get a break early in the second set and hang on to it. I really got on top of him after that."
"I'm still in the fight, nothing is finished today," said Nalbandian. "I have to win the next two matches and I know if I play well I can beat them. I have to work a little bit more."
Federer, who is attempting to become the first player to win three Masters Cups, faces Ljubicic in his next round-robin match on Tuesday.
Red Group: Roger Federer (Swi), Ivan Ljubicic (Cro), Andy Roddick (USA), David Nalbandian (Arg)
Gold Group: Rafael Nadal (Spa), Nikolay Davydenko (Rus), Tommy Robredo (Spa), James Blake (USA)
Monday, 13 November:
Nadal v Blake
Davydenko v Robredo