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 an eighth victory at the All England Club, as he claimed a men’s record 85th win at the tournament.
“I hoped Alex would feel better today but he’s had a rough time recently,” said the 35-year-old. “It’s great to get another win and feel healthy myself.”
Klizan suffered a recurrence of a calf injury that forced him out of tournaments in Rome and Geneva in May, and a groan went around Centre Court when, less than an hour later, Dolgopolov also failed to complete two sets.
The 15,000 spectators were at least cheered by the news that former world number one Caroline Wozniacki and Timea Babos would make a surprise appearance on Centre Court to bolster the schedule.
Three-time champion John McEnroe said on BBC Sport: “I do think when you saw Klizan he clearly wasn’t ready or able to play from the very beginning.
“They’ve got to figure out some kind of rule change where, I suggest, they give him half the first-round prize money and bring someone else in who is at least fit and can go out 110%.
“It’s not a good look for our sport when you have to sit and watch that on Centre Court.