Andy Murray blew hot and cold on his Masters Cup debut in Shanghai today before clinching a 6-4, 1-6, 6-1 victory over Andy Roddick. In the other Red Group match, Frenchman Gilles Simon caused an upset by beating four-times champion Roger Federer.

Murray rattled off three aces in his opening service game and made the crucial break in the fifth. But the British No1 effectively forfeited the second set with a series of unforced errors.

The decider was equally one-sided, only this time Murray was dominant. He took only 25 minutes to despatch the fifth seeded American, clinching victory with a leaping backhand volley.

Murray was satisfied with his performance but did not see himself as the new favourite to win the event. "Everybody is playing very well, and I'll have to play my best in every match if I want to win," he said.

"I don't view myself as being favourite. I have struggled a little bit. It is tough to get over the jet-lag and I hope I feel a bit better for the next match."

In those circumstances, his comfortable victory was encouraging.

"He made it tough for me and made me do a lot of running," Murray said.

"In the first set I thought I played pretty well. In the second, he started to play more aggressively. I felt I was playing better in the final set but it was tough on a very slow court."

Murray earned his place in the end-of-season showpiece following his best year on the ATP Tour, which saw the Scot rise to fourth in the rankings and claim five titles, including back-to-back Masters events in Cincinnati and Madrid.

Meanwhile, Federer's quest for a fifth Masters Cup began badly as he lost 4-6, 6-4, 6-3 against Simon.

The Swiss top seed, who withdrew from the Paris Masters 11 days ago with a back injury, made 50 unforced errors to suffer a second defeat against the 23-year-old Frenchman this season.

"The better you play, the better he plays," said the world No2. "He's quite an unusual player and he makes you work hard.

"I missed shots I normally don't miss. I think that's just lack of practice."

Federer lost his opening match last year against Chile's Fernando Gonzalez but went on to claim the title. "At least now I have three sets under my belt and hopefully I'll play better in the next match," he said.

Simon got his call-up when world No1 Rafael Nadal withdrew through injury.

"It was once again one of the best victories of my career," he said. "I'm really happy to be here. I just wanted to give everything on the court."

Federer had already come back from 40-0 down to save his serve once in the third set when Simon got the better of him to go 5-3 up and he sealed the upset with an ace on his next service game.

"I defeated him in Toronto in July, so it was easier to finish the match," said Simon. "I had no complex when I served in the last game."