Barcelona - Japan's two-time Barcelona Open champion Kei Nishikori won a clay slugfest with Roberto Carballes Baena 6-4, 7-5 on Friday to move into the semi-finals for a fourth time.
Nishikori will take on Russian Daniil Medvedev on Saturday after the seventh seed stopped lucky loser Nicolas Jarry of Chile 6-3, 6-4.
Nishikori, the winner here in 2014 and 2015, served out victory after his 104th-ranked opponent slipped in the penultimate game and appeared to strain a right thigh muscle.
Carballes Baena took an injury time out before returning to court as Nishikori wrapped up the win, his 16th of the season.
"In the first set, everything was working well for me," Nishikori said. "I was hitting my forehand heavy, which I think you need to do on clay."
The contest quickly turned into a series of pounding groundstrokes from both players, Nishikori striking first when he broke in the opening game - enough to claim the first set.
But Carballes Baena struck back in the second, with Nishikori missing on eight break point chances in his opponent's first three service games.
Fourth seed Nishikori finally broke for 6-5 though as Carballes Baena suffered his mishap.
"It was frustrating missing on those break points, I twice had 40-0," Nishikori said. "Mentally it was not easy at all.
"But I knew I was playing well, I tried to stay steady even through he was pushing me, I just tried to play my tennis.
"In the second he started to play better, the last two games were very good tennis for me."
The win was the 22nd here for Nishikori, who has won two of his three matches against Medvedev, including the Brisbane final in January.
"Medvedev is a tough player, he's got a great serve, good reach and he moves well," said Nishikori.
"I'm expecting many long rallies. I need to play aggressive if I want to have a chance at winning."
Rafael Nadal continues his bid for a record 12th Barcelona title in a quarter-final against German Jan-Lennard Struff.
Results from the ATP Barcelona Open on Friday (x denotes seeding):
Kei Nishikori (JPN x4) bt Roberto Carballes Baena (ESP) 6-4, 7-5
Daniil Medvedev (RUS x7) bt Nicolas Jarry (CHI) 6-3, 6-4