Japan's Kei Nishikori suffered a quarterfinal loss against Germany's Alexander Zverev on Friday and crashed out of the Citi Open.

Nishikori, the seventh seed and 2015 champion, was handed a 3-6, 6-1, 6-4 loss by the No. 3 Zverev at Rock Creek Park Tennis Center, falling in a decider after rain delayed the third set for nearly two and a half hours.

The 28-year-old Japanese powered through the first set, breaking the German's serve once and saving two break points. But Nishikori lost momentum in the second as Zverev leaned on his serve, blasting six aces on the way to winning 87 percent of points on first serve.

"After being broken in the second set, my opponent relaxed and started to play better," Nishikori said. "He cranked up his service game and kept delivering in the third set as well."

The 28-year-old Japanese powered through the first set, breaking the German's serve once and saving two break points. But Nishikori lost momentum in the second against six aces from Zverev, and only hit 13 percent of his points on first return.

Nishikori, currently ranked 20th, was making his fifth appearance at the hardcourt tournament -- one of 13 ATP World Tour 500 series tournaments of the season -- since he crashed out in the third round on his 2013 debut.

He defeated American John Isner in 2015 to claim the championship, but did not participate the following year. He made a semifinal exit last year.