The colour had been restored to his cheeks, it had returned to his language and there was a brightened hue to every element of Andy Murray's vast portfolio. Who would have thought the moment that could define a year in which the British No 1 has joined the elite will be a match against Roger Federer when it does not matter if he wins or not.

Putting that prospect to Murray yesterday brought a glance that mixed puzzlement and disdain. That the 21-year-old is through to the Masters Cup semi-finals at his first attempt - and he had to be persuaded that this was so after his 6-4, 6-2 victory over Gilles Simon, of France, yesterday - will have no bearing on the way he approaches playing Federer.

“I'm not going to try and lose to him,” he said. And when you recall that he used to upset the tiddlywinks table if he lost to Jamie, his elder brother, when they were little more than tots, you know what he means.

The destiny of the red group has come down to simple mathematics. If Murray beats Federer tomorrow, the four-times winner is out of the competition and Simon will join the Scot in celebration of two debutants in the semi-finals; if Federer wins, he will top the table and Simon's run is over. And considering that Simon defeated Federer in their opening match, that will have all the indignity of a slap across the cheek, be it velvet-gloved or not.

But such are the intricacies of these round-robin events, it is rare that this stage is reached without there being at least seven variations on a theme. This time, there is no need to have an intimate understanding of the workings of Pythagoras. The gold group has its own play-off for a last-four spot - Novak Djokovic, of Serbia, is through for certain, to be joined by Juan Martín Del Potro, of Argentina, or Nikolay Davydenko, of Russia, who meet today.

Murray could end up losing to Federer tomorrow and face him again in the final. But, as of now, one thing that can be said is that Murray is the perkiest, strongest, most confident player in the mix. There was only a momentary glitch against Simon when, from being on the verge of a 5-0 first-set lead, the Scot was somehow having to stave off two break points that would have brought the score back to 4-4. Other than that, it was picture perfect.

The pursuit of the consummate performance is Murray's quest, which is why he tends to turn the air blue when things do not go his way. While it was impossible from the press seats to hear precisely what he was saying when he did not send every ball to within an inch of the line, it appears that he indulged in some pretty fruity language. The Chinese probably did not understand, but domestic audiences may have been a touch affronted.

One was told that Simon's French vocabulary when the match was slipping from his grasp was as rich as most meals from his home country, so we should not leap to decry Murray too quickly. Why not cherish his brilliant tennis, for there were moments at the Qizhong Stadium yesterday when it reached masterful levels.

Long before the end of the second set, the crux of which arrived when Murray saved three more break points to prevent himself trailing 2-0, Simon had given up the ghost, and he rarely does that. Seeing someone as cerebral as the 23-year-old from Nice swiping at balls in a manner that seemed as if he was not bothered if they went in spoke volumes for Murray's supremacy during the late exchanges.

So Murray has an opportunity for a double avenging of his US Open final defeat by Federer. He beat him fair and square in Madrid on his way to the Masters and wants a repetition. Federer says that he is not 100 per cent physically, his stomach is unsettled and had he been required to play on Tuesday rather than yesterday, he would not have made it. Excuses in early? We shall see.

Murray has earned $275,000 (about £183,000) from the Masters Cup - winning two round-robin matches at $100,000 each and $75,000 of the additional $100,000 he would receive for playing all three group matches. At the US Open, he won $600,000 as runner-up plus an additional $400,000 for his results in the US Open Series, the hard-court events leading into the US Open.

If Murray is the undefeated champion in Shanghai, he will win $1,340,000, $140,000 more than Roger Federer took home for winning the US Open. Rafael Nadal earned £700,000 for his Wimbledon singles triumph. Only Novak Djokovic of the other competitors in the Masters Cup can win the “undefeated champion” prize.

Murray's total prize-money for 2008 entering this tournament is $3,055,648; Nadal has won $6,773,773, Federer $4,936,879 and Djokovic $3,949,077.