Japan's Kei Nishikori pulled off the surprise of this year's Sony Open Tennis event, rallying to defeat red-hot Swiss Roger Federer 3-6, 7-5, 6-3 to advance to the semifinals.

A day after saving four match points en route to upsetting fourth-seeded Spaniard David Ferrer in a grueling three-hour baseline slugfest, Nishikori defeated Federer, the No. 5 seed, Wednesday night to achieve his career best result at this elite hard-court event.

Despite struggling with his serve throughout and putting just 53 percent of his first serves in play over the course of the two-hour match, the Swiss great took the first set comfortably and twice grabbed a service-break lead in the second set.

But Federer began getting bogged down in long baseline rallies as the match wore on, with Nishikori proving more solid in those exchanges and seizing control of the points.

With the Swiss unable to rely on his first serve, he was broken three times and out-aced 5-1 in the second set by his 20th-seeded opponent.

Federer, whose first-serve percentage markedly improved in the third set, saved two break points in the fourth game to even the decider at 2-2.

But Nishikori continued to heap the pressure on to snag one final service break against the 17-time Grand Slam champ, who was unable to find his comfort zone from the baseline.

"Feeling good, of course, to beat Roger," Nishikori was quoted as saying on the ATP World Tour's Web site.

"I thought I really played well, especially in the third. I was hitting both deep and striking well. Everything was going well. There (were a) couple of tough moments, but I was fighting through and happy to win today," the 24-year-old said.

The 32-year-old Federer, who came into the tournament full of confidence after winning a hard-court event in Dubai and losing in the final of this month's BNP Paribas Open in Indian Wells, California, rued his lack of rhythm on the serve but also credited his opponent.

"I could never really get my service games going," Federer said. "On the return, as the match went on, I think it was that Kei started to serve a bit better, which made it more difficult."

Next up for Nishikori in Friday's semifinals will be Serbian world No. 2 Novak Djokovic, who defeated Scotland's Andy Murray 7-5, 6-3 Wednesday afternoon.

In women's quarterfinal action Wednesday, Slovakia's Dominika Cibulkova edged Poland's Agnieszka Radwanska 3-6, 7-6 (7-5), 6-3 in a match that featured a whopping 19 service breaks.

Cibulkova will next take on China's Li Na, a 7-5, 7-5 winner over Denmark's Caroline Wozniacki. EFE