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. Once the ball was a couple of feet away from him, he let it go.”
The Serb, 30, goes on to face Czech Adam Pavlasek in the second round on Thursday as he pursues a third Wimbledon title.
Seven-time champion Federer took his first step towards a record eighth victory at the All England Club.
Canadian sixth seed Milos Raonic, last year’s runner-up, saw off Germany’s Jan-Lennard Struff 7-5 (7-5) 6-2 7-6 (7-4) in his opening match.
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Juan Martin del Potro overcame a battling Thanasi Kokkinakis to seal a 6-3 3-6 7-6 (7-2) 6-4 victory and reach the second round.
The Argentine 29th seed eased to the first set before turning his ankle in the second as the 21-year-old Australian took advantage to level.
A poor tie-break from Kokkinakis handed Del Potro an otherwise even third set.
Kokkinakis then saved six match points in the final game of the fourth set but Del Potro, 28, finally came through.
The former US Open champion will face Ernests Gulbis in round two after the Latvian, ranked 589 in the world, beat the Dominican Republic’s Victor Estrella Burgos 6-1 6-1 6-2.