World number two Novak Djokovic is into the semi-finals of the Madrid Open after his quarter-final opponent Kei Nishikori withdrew with a wrist injury.
Japan's world number eight missed last month's Barcelona Open with the injury and faces a race to be fit for the French Open starting on 22 May.
Defending champion Djokovic will play the winner of Rafael Nadal and David Goffin in Saturday's last four.
It is the Serb's first semi-final since he won the Qatar Open in January.