Wawrinka, who was the top seed, suffered the injury during his second-round victory in three sets against Germany`s Dustin Brown on Thursday.
The French Open champion said: “I twisted my ankle at 5-4 in the first set. I need to see the physios. I have put ice on it but it is less good than I thought.”
Wawrinka had been due to face fifth seed Philipp Kohlschreiber in the quarter-finals so the German will now advance to the last four on a walkover.