Andy Murray moved a step closer to the semifinals of the ATP Tour Finals as the world No 1 wore down Kei Nishikori in a grueling 6-7 (9), 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.

The 29-year-old finally subdued the Japanese star in three hours and 20 minutes, but he was made to wait for confirmation of a last-four berth after Stan Wawrinka beat Marin Cilic 7-6 (3), 7-6 (3) in the evening match.