Andy Murray has claimed that Kei Nishikori put him to work during their round-robin clash at the ATP World Tour Finals at the O2 in London.

The current world number one had to come from a set down to claim a three-set victory in three hours and 20 minutes.

The result has put the three-time Grand Slam champion on the verge of the semi-finals, a feat that he has not reached since 2012.

"I just fought really hard," Murray said on court after the match. "Kei was making me run a lot, he was dictating a bunch of the points. I managed to get enough breaks to win it. That's what you work for is these moments in places like this. It was an amazing atmosphere.

"I feel okay right now. It's normally the next day when you feel stiff and sore but there's hopefully three days left in the season and I'll give my best to get through as many matches as I can."

Novak Djokovic, who is hoping to reclaim his number one ranking by the end of the week, is already into the semi-finals of the tournament after beating Milos Raonic on Tuesday.