Gilles Simon had an enchanting way of describing his victory over Roger Federer, the world No2 and tournament's top seed, that set alight the Masters Cup yesterday. “It was a second accident,” said the Frenchman, having been told that he holds a 2-0 win-loss record against Federer. Not many people can bring that to a dinner-table conversation.

For the second time in successive years at the Qi Zhong stadium, Federer lost his opening round-robin match: for Fernando González, of Chile, in 2007, read Simon, a player of rare ability. The response of Federer 12 months ago was to lay to waste the remainder of his challengers, winning his next four matches in straight sets.

So Andy Roddick, tomorrow, and Andy Murray, on Friday, had better beware of a Swiss with a bruised ego, although the British No 1, who beat Roddick 6-4, 1-6, 6-1 on his competition debut yesterday, could be almost out of range by the time he faces Federer. A straight-sets victory over Simon, whom he defeated in the final of the Madrid Masters last month, would all but guarantee Murray a place in the semi-finals.

Suppressing Simon tomorrow will be an immense task in itself, though, for the tournament's first reserve is playing as well as he ever has and cannot thank Rafael Nadal enough for withdrawing from this event. Speaking of the Spaniard, Nadal said yesterday that he will miss the Davis Cup final against Argentina, which starts in Mar del Plata on Friday week, because of tendinitis in his right knee.

Simon defeated Federer 4-6, 6-4, 6-3, the sting in the tail arriving when the piano-playing, mathematically minded 23-year-old - having had three points to break Federer's serve to lead the final set 4-2 - promptly recovered from facing three against his own to hold for 4-3, break the US Open champion in the next game and hold, with a dashing volley behind his serve, to reach match point. An ace down the “T” settled the outcome.

Simon is a slighter, shorter, less expressive (occasionally) version of Murray. Both players think their way through matches, play this sport as if it is advanced calculus, with theories to be solved, angles to be projected - tennis by slide rules and dividers. Both can do their opponents to death not through the force of personality or games, but because they know the court and its parameters better. Federer, in Simon's case, and Roddick, in Murray's, were outfoxed and reduced to thrashing ineptitude. Both matches were wonders to behold.

What Murray had that Simon did not was a rough patch in the middle of his match that Roddick might have exploited had he truly believed in everything he was doing on the court. Too often, he was trapped between the urge to come forward and recognising the virtues of restraint. Murray loves confused opponents, but it hurt Roddick's reputation, as much as his game, that he decided to take out so much of his ire on hapless ballkids who neither speak his language nor know enough about the irritating idiosyncrasies of some of the players.

That is not something you would expect of Federer, whom Roddick expects “to come out at his best, that's the way I have to prepare”. Murray looked more than a bit ashen in his press conference. “I'm tired, the legs don't quite have the snap in them that they did a few months ago, but I'll try to do my best to recover,” he said.

At least Murray knows what is in store. He has his first Masters cap and he is richer for the experience, both in his head and in the bank, He can freshen up with a couple of his famed ice-baths and, hopefully, catch Simon on the hop. It is fabulously poised.

How they stand

Red group: A Murray (GB) bt A Roddick (US) 6-4, 1-6, 6-1; G Simon (Fr) bt R Federer (Switz) 4-6, 6-4, 6-3.

Gold group: N Djokovic (Serbia) bt J M Del Potro (Arg) 7-5, 6-3; N Davydenko (Russ) bt J-W Tsonga (Fr) 6-7, 6-4, 7-6.

Today: Tsonga v Del Potro; Djokovic v Davydenko.