Eight-time champion Roger Federer avoided a huge Wimbledon upset as injury robbed France's Adrian Mannarino of the chance to earn a memorable win.
Sixth seed Federer, 39, trailed 6-4 6-7 (3-7) 3-6 4-2 when Mannarino slipped and injured his knee.
The world number 41 battled on and lost the fourth set, then retired after one point in the decider.
A sympathetic Centre Court crowd gave a heartfelt ovation as Mannarino, on his 33rd birthday, limped off court.
"It is awful, it shows that one shot can change the outcome of a match, a season, a career. I wish him all the best," said Federer.
"I hope he recovers quickly and we see him back on the courts. He could have won the match."
The Swiss 20-time Grand Slam champion will play France's Richard Gasquet or Japan's Yuichi Sugita in the second round.
More to follow.