Kei Nishikori reached the semifinals of the RBC Tennis Championships on Thursday by beating Diminik Koepfer.
Nishikori, who dropped to world No. 27 after a five-month injury layoff, defeated Germany's Koepfer 7-6 (7-3), 6-3 in a tough 1 hour, 35 minute match at the ATP Challenger Tour event.
The 28-year-old started out in strong shape when he broke his opponent's serve in the third game of the first set, but he gave up the next game. Nishikori bounced back in the second set when he took the first four games, but struggled later on as he handed the next three games to his opponent.
"I was able to bring my rhythm up bit by bit," Nishikori said. "There were times in the second set where I struggled, but I was able to nail my strokes and my serves got better."
"I think I'm doing better than my previous match. I want to work harder," he said.
Nishikori will face world No. 234 Jason Jung of Taiwan in the semifinal.
