Two-time defending champion Kei Nishikori overcame a lackluster start to beat Alexandr Dolgopolov 7-5, 6-0 and advance to the semifinals of the Barcelona Open on Friday.

Nishikori saved four set points before holding on to claim the first set.

"I struggled a little in the first set, but I played well in the second," Nishikori said. "It was great to save that set point. After that I was a different player."

Dolgopolov struggled in the second set, making 32 unforced errors to Nishikori's 16 in the match on the outdoor clay court.

The second-seeded Japanese player will next face sixth-seeded Benoit Paire on Saturday.

Paire came from behind Malek Jaziri 3-6, 7-5, 6-1 in an erratic performance that saw the Frenchman hit six aces and six double-faults.