ANDY MURRAY will hope the complexities of the round-robin system do not come back to bite him again as he bids to reach the semi-finals at the ATP World Tour Finals in London.
THE first year the tournament was held at the O2 Arena three years ago, Murray appeared to have done enough with his two round-robin victories but results conspired against him and he ended up missing out by one game.
Things are not quite so complicated this time around but there are still possible scenarios in Group A where the Scot could beat Jo-Wilfried Tsonga this evening and not qualify or lose and go through.
The Scot's path was made more tricky by his loss to Djokovic on Wednesday but he has no complaints about the system and insists it will not weigh on his mind tonight.
"We're not really used to it in tennis because we play knockout everywhere else," said Murray. "But that's just the way this tournament's always been.
"There's no point in changing it. That's the tradition of this tournament. It's absolutely fine. You need to try and view it like it's a knockout and try to win the first couple of matches, get yourself safe if you can."
Roger Federer became the first singles player to qualify yesterday when he defeated David Ferrer 6-4 7-6 (7-5) - his second straight-sets win of the tournament.
It is the 10th time in 11 years that Federer has made the semi-finals, only missing out in Shanghai in 2008, while he is going for his seventh title and third in a row at the O2 Arena.
A win for Juan Martin Del Potro over Federer tomorrow would put the Argentinian through as well after he defeated Janko Tipsarevic 6-0 6-4.