PARIS — For two sets and more than two hours at the French Open on Monday, Novak Djokovic found himself being outplayed by a 19-year-old opponent from Italy making his Grand Slam debut.

And yet, to hear Djokovic tell it afterward, he had the kid right where he wanted him. Which turned out to be true.

Rafael Nadal also faced an Italian who’s just 19 in the fourth round — and also took a bit of time to get going. Nadal’s trouble lasted all of eight games and less than 45 minutes Monday before he took control, ran his Roland Garros streak to 35 consecutive sets and joined Djokovic in reaching a record 15th quarterfinal at the clay-court major tournament.

After dropping a pair of tiebreakers, Djokovic suddenly went from a big deficit to his best tennis. He grabbed 13 games in a row before Lorenzo Musetti stopped playing because of lower back pain and cramps while trailing 6-7 (7), 6-7 (2), 6-1, 6-0, 4-0.

“I like to play young guys in best-of-five, because I feel even if they are leading a set or two sets to love, as it was the case today, I still like my chances,” said the top-seeded Djokovic, who is 34, “because I feel like I’m physically fit and I know how to wear my opponent down.”

Nadal, who turned 35 last week, trailed 5-3 early on against the 18th-seeded Jannik Sinner, who served for the first set at 5-4.

“I was playing a very good player with a big future,” Nadal said.

But 13-time French Open champion Nadal took eight games in a row and, after a blip in the second set, resumed his excellent play and closed his 7-5, 6-3, 6-0 win on a 10-game run.

Musetti, a talented Italian so good at the outset with his one-handed backhand and tremendous touch, is hardly used to this best-of-five-set format at the majors and he took a medical timeout after the fourth.

“It didn’t make sense to keep playing. I couldn’t win any points or stay in the rallies. It was hard for me to move,” Musetti said. “I was at my limit.”

Djokovic wound up 9 for 9 on break-point chances.