Roger Federer opened his quest for a seventh season-ending tour title looking like the man to beat - again.
The 17-time Grand Slam champion won his record 40th match at the tournament, defeating Janko Tipsarevic 6-3, 6-1 Tuesday in his opening Group B match.
Federer lost only eight points on his serve under the roof of the O2 Arena while converting four of his nine break points.
"Obviously, come in knowing that I've played so well past years, I expect myself also to be at a solid level," said Federer, who also won his seventh Wimbledon title this year and won a silver medal at the London Olympics. "I've had a good year. It's true, I feel like I'm striking the ball well after today. I hope it's a sign for more to come hopefully."
Federer's presence alone breathed a bit of life into the tournament for the top eight players in the world.
A day after Andy Murray made his return to Britain for the first time since winning the US Open, the crowd actually got into Tuesday's match, complete with cowbells ringing and constant chanting for Federer.
"I'm very, very honored, really, and very proud in some ways to be so well liked by so many fans around the world, just not in one particular place or one country," said Federer, who will next face David Ferrer on Friday (NZ time). "It really seems to be everywhere I go I get a lot of fan support."
The Swiss star didn't disappoint them, looking like he was right at home right from the start.
He held at love to open the match, and immediately broke Tipsarevic for a 2-0 lead that held the rest of the way. In the second set, Tipsarevic held serve to start, but couldn't win another game as Federer even dazzled the fans with a couple of behind-the-back hits off Tipsarevic serves that had nipped the net.
"The problem was that he got an early break in both sets," Tipsarevic said. "Everybody knows that when Roger starts leading, he is probably the best player in the world when he's a break up early in the set."
Tipsarevic was playing for the first time since retiring from his quarterfinal match at the Paris Masters last week, saying he was dizzy and fatigued.
"I felt good in the first set. Even though I lost it, I didn't lose the first set because I was feeling bad, whatever. But later on when we played these longer rallies, my serve started to suffer a little bit," Tipsarevic said of today's match against Federer. "But I'm feeling better day after day after day."
Federer didn't even play in Paris, instead pulling out to rest up for London.
"I still had some little things I had to work through the last couple of days. Really since yesterday, I feel fine," Federer said. "So obviously it was good for me to start on Tuesday."
Federer twice won the season-ending tournament when it was in Houston in 2003-04, and then won two more in Shanghai in 2006-07. In London, he is the two-time defending champion.
Tuesday's victory moved him out of tie with Ivan Lendl for the most wins at the tournament with 40.
In the late Group B match, Ferrer beat Juan Martin del Potro 6-3, 3-6, 6-4.