Andy Murray could have to play three times on Saturday after his Munich Open quarter-final against Lukas Rosol was postponed because of rain.
The Briton, travelling with coach Jonas Bjorkman this week for the first time, is trying to win his first clay title.
Should top seed Murray beat Rosol on Saturday morning, he will play Roberto Bautista Agut or Victor Estrella Burgos in the semi-final later in the day.
Murray is then scheduled to play the doubles semi-final.
The Scot, who has teamed up with Dutchman Jean-Julien Rojer in the doubles, had a bye in round one of the singles and
Philipp Kohlschreiber plays David Goffin, and Dominic Thiem takes on Gerald Melzer in the other half of the draw.
At the Istanbul Open, world number two Roger Federer battled past Spain's Daniel Gimeno 7-6 (7-3) 6-7 (5-7) 6-3 to reach the semi-finals.
The 33-year-old Swiss will play eighth seed Diego Schwartzman of Argentina in the last four.