PARIS (AP) Novak Djokovic withdrew from the French Open with an injured right knee on Tuesday, ending his title defense and meaning he will relinquish the No. 1 ranking.

The tournament announced the news, saying Djokovic has a torn medial meniscus in his right knee. The extent of the injury was found during an MRI exam a day after Djokovic was hurt during a fourth-round victory against No. 23 Francisco Cerundolo that lasted five sets spread across more than 4 1/2 hours.

The 24-time Grand Slam champion was supposed to face two-time French Open runner-up Casper Ruud in the quarterfinals on Wednesday. Instead, Ruud gets a walkover into the semifinals, where he will face No. 4 Alexander Zverev or No. 11 Alex de Minaur.

Djokovics knee had been bothering him for a couple of weeks before he arrived at Roland Garros something he kept to himself until after the win against Cerundolo. Early in the second set Monday, Djokovic tweaked his knee and took a medical timeout. A trainer worked on the joint then and during subsequent changeovers, and Djokovic took what he said a tournament doctor told him was the maximum dose of pills allowed to dull the pain and reduce any inflammation.