Andy Murray is on course to record the biggest win of his career at the Masters Cup in Shanghai.

Murray marked his debut at the season-ending showpiece by out-serving Andy Roddick and tomorrow he will face Gilles Simon, who produced a shock victory over four-times champion Roger Federer.

Victory would guarantee the British No1 a place in the semi-finals, though jet-lag may prove to be the most difficult opponent Murray has to conquer.

He said: "I'm tired and my legs don't quite have the snap in them that they did a few months ago.

"It's tough to get over the jet-lag. I've been going to bed at this time and hopefully I'll be better for the next match. I'll do my best to recover for the next match.

"I guess the chances of me qualifying have gone up pretty significantly after me winning and Federer losing.

"But in terms of winning it, I have to win three more matches to do that."