Japan's Kei Nishikori
Japan's Kei Nishikori trains at the O2 Arena in London November 7, 2014. The men's ATP World Tour tennis finals take place at the O2 Arena from Sunday for a week. Reuters

Kei Nishikori defeated replacement player David Ferrer in three sets, 4-6, 6-4, 6-1 to gain his second win at the 2014 ATP World Tour Finals at the O2 Arena in London, United Kingdom. The victory put closer the Japanese to a semifinal appearance depending on the result of the Roger Federer vs. Andy Murray tiff on Friday.

Ferrer spotted for Canadian Milos Raonic, who was out of commission due to a quad tear. Raonic was virtually out of the running already with two losses— to Federer and Murray— in his first two matches of the season finale.

Although there was no chance that he’d advance to the final four in London, Ferrer played true to form in the first set taking it, 6-4. Nishikori, who had four double faults in the opening set, shook off the nerves in the second to tie the match at one set apiece to force the deciding third set.

The Japanese completed the comeback win convincingly in the decider saving five break points and breaking the Spaniard three of four times to gain the 6-1 set win and finish the match a little under two hours (1:56:59). Nishikori raced to a 4-0 lead in the third and never let up.

2014 ATP World Tour Finals - Semifinal Scenarios

Nishikori, who is the first Asian player to play in the season-ending tournament, now awaits the result of the crucial Federer vs. Murray match. If Murray loses the match against the Swiss Maestro, the home country bet is out and if Murray doesn’t win in straight sets, Nishikori and Federer will go through to the semifinals of the 2014 ATP World Tour Finals owing to tiebreaker rules.

Federer clinched a place in the semifinal round by virtue of superior total sets record, thanks to Ferrer winning the first set against Nishikori. The Andy Murray vs. Roger Federer tiff, the final game in the group stage for Group B, is set at 8pm in London, 7am in Australia.