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 28 May.
Defending champion Djokovic will play the winner of Rafael Nadal and David Goffin in Saturday's last four.
Simona Halep reached the women's final with victory over Anastasija Sevastova.
The Romanian third seed beat the unseeded Latvian 6-2 6-3 and will face France's Kristina Mladenovic or Russian Svetlana Kuznetsova in the final.