Former champions Roger Federer and Novak Djokovic both reached the second round at Wimbledon without completing matches after their opponents retired.
Third seed Federer led 6-3 3-0 when Ukrainian Alexandr Dolgopolov quit with an ankle injury after 43 minutes.
The Centre Court crowd had already seen second seed Djokovic progress after a calf injury saw Martin Klizan pull out at 6-2 2-0 down on 40 minutes.
"You never like to end up a match this way," said Djokovic.
"I heard that Klizan had issues even before walking on the court. You could see he wasn't moving.