PARIS (AP) — Novak Djokovic was laying on his back on a French Open sideline early in the second set Monday, wincing while his injured right knee was manipulated by a trainer — and worrying that he might need to quit playing the match.

After stumbling and limping around, then finding himself down by a set and a break against a younger, eager opponent, Djokovic regained his verve with the help of what he said a tournament doctor told him was the maximum dose of pills allowed to dull the pain and reduce any inflammation.

So, yes, Djokovic kept at it and came back to win in five sets across about 4 1/2 hours for the second consecutive time, surging past No. 23 Francisco Cerundolo 6-1, 5-7, 3-6, 7-5, 6-3 in the fourth round at Roland Garros for his record 370th win in a Grand Slam match. But here’s the catch: Djokovic said he could not be certain whether he would be healthy enough to play in the quarterfinals on Wednesday.

“I don’t know what will happen tomorrow — or after tomorrow, if I’ll be able to step out on the court and play,” the 37-year-old Djokovic said. “You know, I hope so. Let’s see what happens.”

READ MORE 17-year-old Andreeva reaches her first French Open quarters by beating last Frenchwoman De Minaur is a firm clay court believer after reaching the French Open quarterfinals Grigor Dimitrov vs. Jannik Sinner and Carlos Alcaraz vs. Stefanos Tsitsipas in French Open quarters

Djokovic said the knee has bothered him for a couple of weeks, chalking it up to wear and tear, and it got worse after he tweaked it against Cerundolo. Djokovic took a medical timeout at 2-1 in the second set, was treated by the trainer on subsequent changeovers, and was given more medicine after the third set.

“I didn’t know, to be honest,” Djokovic said, “whether I should continue or not.”

Eventually, he felt better and could move without restrictions, and his level of play soared accordingly.

This was the second consecutive five-set comeback victory that lasted about 4 1/2 hours for Djokovic, who is ranked No. 1 and the defending champion in Paris. He said that accumulation of time was not a problem; his knee was, however.

Djokovic is supposed to meet No. 7 seed Casper Ruud on Wednesday. Ruud, who eliminated No. 12 Taylor Fritz 7-6 (6), 3-6, 6-4, 6-2 Monday, lost to Djokovic in the French Open final last year and to Rafael Nadal in the 2022 title match.

“The effect of the medications will not last for too long, so I’ll see,” Djokovic said. “I guess we’ll do some more screening and tests and checkups tomorrow.”

The questions about his status took attention away from the latest in the long series of Djokovic’s monumental achievements. Beating Cerundolo allowed Djokovic to break a tie with Roger Federer for the most match wins at major tournaments — and also for the most Slam quarterfinals for a man, reaching the 59th of his career.

But just barely. Djokovic trailed by two sets to one, and was down a break at 4-2 in the fourth, putting him two games from defeat.

“I was,” Djokovic said afterward, “maybe three or four points away from losing this match.”

Still, he came through in ways he has so often over his years of dominance and 24 major trophies, a total that includes three at the French Open. He both turned around a contest after trailing — go ahead and ask Federer about holding match points against the guy — and emerging when the tension is greatest. Djokovic is 40-11 in fifth sets over his career; compare that with Cerundolo’s 1-3 mark, and the outcome should surprise no one.

“Really, the toughest guy ever to play tennis,” Cerundolo said. “He always finds a way to come back and play his best tennis at the toughest moments and at the end of every match.”

At 2-1 in the crucible of the fifth set, Djokovic’s feet gave way as he chased a ball to his right, and he rolled on the ground, caking his white shorts, his red shirt and parts of his arms and legs with the rust-colored clay. As he walked to the sideline to grab a bottle of water to clean off, he gave a piece of his mind to anyone who would listen, renewing an earlier complaint about wanting the court to be swept to improve traction.

“Well done, supervisor and everybody,” Djokovic said, his voice drenched in sarcasm. “Not slippery at all.”

At his news conference, he restated his concerns and his disappointment in the decision to not do more about the clay.

“I mean, today I injured myself. Yes, I survived. I won the match. Great. But will I be able to play next one?” he said, tapping his palms on a table for emphasis. “I don’t know. I don’t know the severity of the injury. But could have this injury be prevented? Possibly, if there was just a little bit more of a frequent care of the court during the set.”

In the third round, he made his way past No. 30 Lorenzo Musetti, a 22-year-old from Italy, finishing Sunday after 3 a.m., the latest finish in French Open history.

Against Cerundolo, a 25-year-old from Argentina who was trying to reach his first Grand Slam quarterfinal, Djokovic again used all of his skills, experience and ability to adjust on the fly. He came through, in part, by putting extra speed on his groundstrokes.

From 3-all in the fifth, Djokovic grabbed every remaining game. That included breaking to lead 5-3 with a forehand winner that caught the baseline — so close to being out that chair umpire Aurélie Tourte climbed down to check.

The other men’s quarterfinal Wednesday will be Alex de Minaur, who beat 2021 U.S. Open champion Daniil Medvedev, against Alexander Zverev, a 4-6, 6-1, 5-7, 7-6 (2), 6-2 winner against Holger Rune in a match that ended at 1:40 a.m. on Tuesday.

The women’s quarterfinals on Wednesday: Aryna Sabalenka vs. Mirra Andreeva, and Elena Rybakina vs. Jasmine Paolini.

With temperatures topping 70 degrees Fahrenheit (20 Celsius) after a tournament of chillier weather and plenty of rain — a shift in conditions that Djokovic thought affected the amount of clay on the playing surface — the azure sky was visible, finally, as Djokovic and Cerundolo began in the late afternoon.

Djokovic’s comeback truly began in the evening, at 4-3 in the fourth, when he smacked a winner to earn a break point — not to mention roars from the stands — and converted when Cerundolo netted a shot. Djokovic shook his racket overhead, and a chant of his two-syllable nickname rang out, “No-le! No-le!”

He arrived in Paris with just a 14-6 record in 2024 and not one appearance in a tournament final, let alone a title. Sure, he’s been living on the edge so far at the French Open — his past two matches required 9 hours, 8 minutes over 10 sets — but no one ever has been as good as Djokovic at Slam time. So long as he can play at all, that is.

___

AP Sports Writer Jerome Pugmire and Associated Press writer Tom Nouvian contributed to this report.

___

AP tennis: https://apnews.com/hub/tennis