World No 3 Carlos Alcaraz withdrew from the Madrid Open on Thursday with a thigh injury, in a blow for his French Open title defence preparations.
The Spaniard, a four-time Grand Slam winner, sustained the problem during his Barcelona Open final defeat last Sunday by Holger Rune.
"I did everything that was in my hands but it didn't improve a lot over the (last few) days," Alcaraz told a news conference.
"Things didn't work out as I wanted to be able to play here, and we have decided not to take risks.
"If I played, I was going to be messed up for longer than expected... hard decisions had to be made, and I think we made the right one."
Alcaraz was hoping to lift the trophy in Madrid for the third time after his 2022 and 2023 victories.
The 21-year-old had not trained all week after arriving in the Spanish capital on Monday.
The Spaniard did not rule out competing in the Italian Open and said he was sure he would make the French Open.
"I think I will definitely be at Roland Garros and I will do everything possible to be in Rome," said Alcaraz.
"On Monday I'll have another test to see how it's evolved, and from there we'll take the times and evaluate how the next few weeks are going to be and how my body is doing."
The French Open main draw begins on 25 May.