Roger Federer pulled out of the French Open on Sunday to give his 39-year-old body time to recover for Wimbledon.
The Swiss great was forced to cut his Roland Garros stint short after he was stretched to his limits during a 7-6, 6-7, 7-6, 7-5 win over Germany's Dominik Koepfer on Saturday night.
"After discussions with my team, I've decided I will need to pull out of Roland Garros today," Federer said in a statement on Twitter.
"After two knee surgeries and over a year of rehabilitation it's important that I listen to my body and make sure I don't push myself too quickly on my road to recovery."
The game against Koepfer lasted over three-and-a-half hours and was played on an empty Court Philippe Chatrier, finishing well past midnight. Federer, who will turn 40 in August, has decided to thus concentrate on preserving his body.
Federer was set to take on Matteo Berrettini on Monday for a place in the quarter-finals.
"I don't know if I am going to play," Federer had said after his late finish on Saturday. "I have to decide whether or not to continue. Is it too risky to keep putting pressure on the knee? Is it a good time to rest?
— Roger Federer (@rogerfederer) June 6, 2021
"Every match I have to reassess the situation and see the next morning in what state I wake up and how my knee is doing.
"It may be even more true after a match as long as the one tonight."
Federer was playing only his third tournament since last year's Australian Open and has always stated Wimbledon is his main target. He is chasing a ninth title at Wimbledon, which starts on June 28.
The Swiss great is also scheduled to play the warm-up grass court tournament in Halle beginning on June 14, the day after the French Open ends.
Federer said: "These are all stepping stones to something that is really important to me.
"We go through these matches, we analyse them highly and look on what's next. Because I need to decide if I keep on playing or not or is it not too much risk at this moment to keep on pushing or is this just a perfect way to just take a rest.
"Because I don't have the week in between here and [the grass-court tournament in] Halle like normal, to see what's best now if you count back from Wimbledon."
