The writing was on the wall for Stefanos Tsitsipas at London's 02 Arena on Thursday night

Credit: EPA

Rafael Nadal kept alive his hopes of winning the year-ending ATP Finals for the first time as he beat Greek defending champion Stefanos Tsitsipas 6-4, 4-6, 6-2 on Thursday.

The last round-robin match in the London Group was a straight knockout with both men having lost to Dominic Thiem and beaten Andrey Rublev earlier in the week.

But it was Spaniard Nadal who always appeared the likely winner despite a lapse which allowed Tsitsipas to extend the contest into a decider at a near-deserted O2 Arena.

After a flurry of service breaks at the start of the third set, the 34-year-old Nadal pulled away to reach the semi-finals for the first time in five years.

As group runner-up behind Thiem, he will face Daniil Medvedev for a place in the final with the Russian assured of top spot in the Tokyo Group.

"In general this was a very positive match for me," said Nadal, who despite winning 20 Grand Slam titles has only two runners-up places to show for his previous nine appearances at the ATP Finals. "Excited to be in the semi-finals."