Shanghai:Britain's Andy Murray said he's looking to deliver the knock-out blow to ailing Masters Cup champion Roger Federer, whose bid for a fifth title has been hit by an untimely stomach complaint.
Murray, 21, said he was gunning to send Federer crashing out with a fourth career win -- and the second in a month --against the former world number one.
"You try and win. I'm not going try and lose to Federer," he said ahead of their Red Group clash tomorrow.
"I've beaten him three times. I'd like to make it four." Murray is at a career-high fourth ranking and his confidence was lifted further by a straight-sets dismissal of French threat Gilles Simon to reach the semi-finals.
"To beat a couple of top-10 players back-to-back is great. The Masters Cup is obviously a huge, huge competition for all the top players. I've got a chance of winning it now," he said.
An out-of-sorts Federer meanwhile ground out a victory over Czech alternate Radek Stepanek, who was called up at the last minute after Andy Roddick rolled an ankle in training.
Murray, widely tipped to end Britain's 76-year Grand Slam drought, is already through to the semi-finals but said he wouldn't hold back against the two-time defending champion.
"I don't try and find a balance. I try and beat Federer.
Ideally I'd like to knock him out of the competition if I can," he said.
"I'd rather not have to play him twice in one week. He's the best player ever."
The in-form Murray beat Roddick in his opening match and is now arguable favourite for the title. Federer, who is recovering from a back injury, lost to Simon in his first match before being hit by the stomach bug.
Looking pale and unsteady after playing Stepanek, he said he spent all of Tuesday holed up in his hotel room and claimed it would take a "miracle" to reach the semis.
"Woke up in the morning and I was feeling terrible. Really upset stomach and couldn't even practice. Didn't go out of the room. Just sort of trying to get over things," Federer said.
"At the end of the day I still have a chance. I hope with a day of recovery, I'll make a miracle happen here and get through into the semis."
Federer almost pulled off a miracle in 2005 when he struggled through the tournament with an ankle injury before losing an epic final to David Nalbandian.
The 27-year-old is bidding to become only the third player to win five year-end titles after Ivan Lendl and Pete Sampras. Lendl completed the last hat-trick in 1987.