Carlos Alcaraz withdrew on Wednesday from the Barcelona Open because of a wrist injury that troubled him in his first-round match, potentially casting doubt over his Roland Garros defence.
"I won't be able to continue in the tournament," Alcaraz told reporters a day after his win over Finnish qualifier Otto Virtanen.
"I felt my wrist give out on a return during the match. After the tests, we saw that it's a more serious injury than any of us expected, and I have to listen to my body so it doesn't affect me in the future."
It is the second time in three years injury has forced Alcaraz to withdraw from the Barcelona tournament. He won it 2022 and 2023, and finished runner-up to Holger Rune 12 months ago.
Alcaraz had been scheduled to face Tomas Machac on Thursday for a place in the quarterfinals.
"I have to go home to start my recovery as soon as possible with my team, the doctors, and the physical therapist, and get — or try to get — as healthy as possible as soon as possible for the tournaments I have coming up," the Spaniard said.
"I hope you'll be able to see me on the court again as soon as possible."
Alcaraz received a medical timeout at the end of the first set during his 6-4, 6-3 win over Virtanen on Tuesday but did not show any signs of physical discomfort.
He said he hoped it was "nothing" after the match and that without time to rest between tournaments that it was normal to have "little niggles".
Alcaraz lost his world number one ranking this week following his defeat by Jannik Sinner in the Monte Carlo Masters final on Sunday.
He would have had a chance to regain it by winning the title in Barcelona, with Sinner not playing this week.
The 22-year-old Alcaraz became the youngest man to complete the career Grand Slam in January with his triumph at the Australian Open.
He holds a 22-3 record this season and also won a title in Doha.
Alcaraz said earlier this month he was hoping to play a full season on clay before starting his French Open title defence in late May.
Last year he won in Monte Carlo but skipped the Madrid Open, returning in Rome to lift the trophy there for the first time.