LONDON-Andy Murray moved a step closer to the semi-finals of the ATP Tour Finals as the world number one wore down Kei Nishikori in a gruelling 6-7 (9/11), 6-4, 6-4 victory that took over three hours on Wednesday.

Murray was pushed to his limits by Nishikori in the longest Tour Finals match played in the event's seven years at London's O2 Arena. But Murray finally subdued the Japanese star in three hours and 20 minutes and will be guaranteed a place in the last four if Marin Cilic defeats Stan Wawrinka on Wednesday evening.

"I just fought really hard. Kei was making me run but I eventually got over the line," Murray said. "These are the sort of matches you work so hard for. I feel OK right now, but it's the following day when you feel it often. Hopefully there will be another three days to this season and I'll do my best to get through them."

The 29-year-old's gritty recovery took his winning streak to 21 matches, just one short of his career best run of 22 successive victories earlier this year. It is the first time Murray has started the Tour Finals with two consecutive group stage wins since his tournament debut in Shanghai in 2008. Murray's refusal to be outlasted by the obdurate Nishikori keeps him on course to retain top spot in the ATP rankings at the end of the year.

Novak Djokovic's win over Milos Raonic on Tuesday had given the Serb a 70-point lead over Murray in the unofficial 'as-it-stands' rankings but, with each victory at the Tour Finals worth 200 points, the Scot moved back above his old rival by beating Nishikori.

Murray has enjoyed an incredible 11 months in which he has won Wimbledon for the second time, claimed a second Olympic singles gold medal and lifted four successive titles in Beijing, Shanghai, Vienna and Paris.

But since losing to Djokovic in the French Open final in June, the highest-ranked player Murray had faced was then world number six Milos Raonic in Cincinnati.

Djokovic beats Raonic to book last four spot: Novak Djokovic booked his place in the semi-finals of the ATP Tour Finals with an emotional 7-6 (8/6), 7-6 (7/5) victory over Milos Raonic on Tuesday night.

Despite having a spiritual guru in his camp these days, Djokovic has been anything but serene lately and once again the defending champion cut an angst-ridden figure for long periods of a tense clash in the prestigious season-ending event at London's O2 Arena. Djokovic had reacted furiously after being grilled by the media about a potentially dangerous incident when he slammed a ball into the stands during his win against Dominic Thiem on Sunday.

This time, the world number two grumbled over camera flashes from the crowd and held a finger to his lips to urge them to be quiet, while moaning when Raonic tried some gamesmanship by taking his time tying up his shoelaces at a key moment in the first set tie-break.

But, to his credit, Djokovic handled everything a fired-up Raonic threw at him to ensure he remains on course to win the Tour Finals for a fifth successive year and record-equalling sixth time in total. The 29-year-old, who has now won 20 of his last 21 matches at the Tour Finals, would also regain the number one ranking from Andy Murray if he leaves south London with the silverware.

"I managed to hang in there mentally and stay strong and believed that the opportunities would come and that I could take them," Djokovic said. "Milos was hanging in there and only one or two points separated us in the second set. It could have gone either way this match. He's such a strong player and has got firepower."


LONDON: Novak Djokovic in action during his round robin match of the ATP World Tour Finals against Canada's Milos Raonic.–Reuters