Jannik Sinner moves to the top of world rankings after reaching French Open semis

While the Italian was beating Dimitrov in straight sets, Novak Djokovic withdrew from the tournament with a knee injury.

Djokovic's departure means Sinner will rise above the Serbian to the top of the rankings when they are updated on Monday.

The 22-year-old, who is the first man from Italy to be world number one, sank Bulgarian veteran Dimitrov.

"It means a lot to me for sure," he said. "It's not the way we all were expecting actually. He had two very long matches, tough matches, five sets, so it's tough. The first one he finished really late also.

"You know, it's tough also for the tournament. Novak retiring, it's always tough.

"Talking about myself, I am very happy about this achievement. It's a lot of work we put in daily. It's a daily routine. Obviously I'm happy to have this number.

"In two days there is a very important match for me, the semi-finals, so I'm focused about that at the moment. But, yes, of course, very happy to have this number now."

Sinner will play fellow young gun Carlos Alcaraz, who until last September was world number one himself.

Alcaraz, 21, claimed he had the "key" to beating Stefanos Tsitsipas ahead of their night session quarter-final.

And the Wimbledon champion was as good as his word, overpowering the Greek ninth seed 6-3 7-6 (3) 6-4.

Tsitsipas made a brief fight of things in the second set, and complained of hindrance to the umpire following one elongated Alcaraz grunt during the tie-break.

But a double-fault midway through the third set gifted Alcaraz the initiative and the Spaniard duly took his head-to-head with Tsitsipas to six wins from six matches.

"I think it was a very good match, I played great," said Alcaraz. "I controlled very well my emotions and was really calm in the moments I had to be. I'm really happy to play a semi-final here in Roland Garros.

"Jannik will be a really difficult challenge, right now he's the best player in the world, the player playing the best tennis right now.

"We've played some great, great matches. Thanks to him I push myself to be a better player, to improve my game to try to beat him. I'm ready to take that challenge."

READ MORE: Novak Djokovic pulls out of French Open with knee injury