Roger Federer produced an excellent display to end Novak Djokovic's unbeaten run indoors ©Getty Images

Switzerland’s Roger Federer booked his place in the ATP World Tour Finals semi-finals after ending Novak Djokovic’s three-year unbeaten record indoors as he overcome the Serbian in straight sets at the O2 Arena in London.

With both players having secured victories in their opening group matches, the victor in the contest was assured of a spot in the last four of the season ending tournament, featuring the top eight men’s players throughout the year.

World number one Djokovic looked most likely to break in the early exchanges but several fine serves from Federer saw the 17-time Grand Slam winner keep pace with the Serbian to leave the first set appearing destined for a tie-break.

The Swiss though upped the pressure on Djokovic’s serve with the score at 6-5 and despite seeing a first break point pass him by he secured another chance to seal the set which he took with aplomb, as a well-placed volley brushed the baseline out of the Serbian’s reach.

A stunning start to the second set saw both players trade breaks but with Djokovic making uncharacteristic unforced errors, Federer began to take control and the 34-year-old broke on two further occasions to wrap up a 7-5, 6-2 win to end Djokovic’s 38-match winning run indoors.

"It's always a thrill to come out here, even more so against a great player like Novak,” Federer said afterwards.

“It's a special night for tennis, and a cool atmosphere.

"The tactic was to mix it up, I have to against Djokovic."

Kei Nishikori held off a Tomas Berdych fightback to earn his first win of the tournament
Kei Nishikori held off a Tomas Berdych fightback to earn his first win of the tournament ©Getty Images

Japan’s Kei Nishikori boosted his prospects of earning a semi-final place after holding off a fightback from the Czech Republic’s Tomas Berdych to claim a three set win.

The number eight seed had been ruthlessly exposed by Djokovic in his first round robin match but a more composed start against Berdych saw him take the opening set 7-5.

Berdych though recovered from a break down in the second set to level the match, however the momentum swung back Nishikori’s way in the decider with the Japanese star battling to a 7-5, 3-6, 6-3 win.

Nishikori will now face Federer in his final round robin tie on Thursday (November 19), while Djokovic will hope to bounce back from defeat when he faces the winless Berdych.

India’s Rohan Bopanna and Romania’s Florian Mergea continued to belie ranking in the doubles event as the eighth seeds claimed their second win of the tournament, defeating Britain’s Jamie Murray and Australia’s John Peers 6-3, 7-6.

Meanwhile America’s Bob and Mike Byran earned their first victory after brushing aside Italy’s Simone Bolelli and Fabio Fognini 6-3, 6-2.

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