Andy Murray has taken a swipe at Madrid Open organisers for making him play his second-round match in the early hours of the morning earlier this week.
The world number three did not leave the court until 2am (BST) following his victory against Philipp Kohlschreiber, and he was back in action less than 24 hours later to take on Marcel Granollers yesterday afternoon.
Murray showed little signs of fatigue as he claimed a comfortable straight-sets win in the Spanish capital, but he admitted afterwards that he was certainly feeling the effects.
"I felt very tired today," he is quoted as saying by BBC Sport. "If they want to see the top players playing the best tennis, don't have them play matches at three o'clock in the morning.
"I tried to pump myself as much as possible for this match and bluff [Granollers] to show I was feeling OK."
Milos Raonic, who beat Argentina's Leonardo Mayer 6-4 6-3 in the third round, awaits Murray in today's quarter-final.