Novak Djokovic moved into the semi-finals of the Madrid Masters on Friday without hitting a ball as Kei Nishikori withdrew citing the recurrence of a wrist injury, tournament organisers said.
The Japanese world number eight missed the Barcelona Open late last month due to the injury.
Nishikori is now also a major doubt for the Rome Masters next week with 10 days to go until the start of the French Open.
Djokovic will either renew his rivalry with Rafael Nadal or face Belgium’s David Goffin in the last four on Saturday.