World No.1 Novak Djokovic reached his 10th French Open semi-final but suffered an injury scare before beating Spain’s Pablo Carreno Busta 4-6 6-2 6-3 6-4 on Wednesday.

A month after being defaulted for striking a line judge with a ball while playing Carreno Busta in the US Open fourth round, the 33-year-old Serbian found himself in trouble once again.

This time it was nothing more sinister than pains in his neck and arm as Djokovic lost the opening set to the 17th seed – the first one he has dropped in the tournament.

Djokovic looked flat and had to save break points early in the second set before raising his game to level the match.

It looked plain sailing when he led 3-0 in the third set before a dip allowed Carreno Busta back but Djokovic saved a break point at 3-3 before pulling away.

Djokovic, bidding for a second French Open crown, produced several loud roars as he tried to fire himself up.

Carreno Busta hung on gamely but Djokovic was superior in the big moments and one break in the fourth was enough to set up a semi-final clash with Stefanos Tsitsipas.

“Many players have said it before me: these four grand slams matter the most in tennis history,” Djokovic said afterwards on Court Philippe Chatrier on another damp and chilly night.

“They are the most popular tennis events in the world and a lot of kids dream of winning them.”

Greek star Tsitsipas produced a clinical performance to storm to a 7-5 6-2 6-3 victory over Andrey Rublev.

Tsitsipas’s only moments of concern came in the opening set when Russian Rublev, the 13th seed, made a brisk opening to lead 5-3.

Yet four games later, Rublev had surrendered the set, and barely more than an hour later, he had lost the match, winning only five more games in what proved a one-sided encounter with the No.5 seed.

“I’ve been feeling really comfortable on this court and despite a bad start and being a break down I remembered what a big fighter I am,” Tsitsipas told the sparse crowd on Court Philippe Chatrier afterwards.

“It’s about fighting and trying to find solutions at difficult moments. I managed to get my brain working and found solutions.

“Roland Garros is a tournament I have been watching since I was a kid and always dreamed of playing on these courts.

“I used to skip classes at school to watch it. That’s how much I like this tournament. It’s a dream come true playing here and in front of the public.”

Tsitsipas had led by two sets and 5-1 only to lose to Borna Coric at the US Open last month, and just last Sunday in the Hamburg final he served at 5-3 up in the deciding set against Rublev, only to lose it 7-5.

There was no such drama here, though, as the 22-year-old held to love, finishing Rublev off with a volley at the net to reach his second grand slam semi-final and his first in Paris.

Kenin extends winning run

In the women’s draw, Australian Open champion Sofia Kenin has extended her outstanding run of success at grand slams this year by beating an injury-hit Danielle Collins 6-4 4-6 6-0 to reach the French Open semi-finals.

In the last four, the American will face Czech Petra Kvitova, who had earlier overcome some nervy and potentially costly double-faults to beat 66th-ranked Laura Siegemund 6-3 6-3.

Sofia Kenin in action during her win over fellow American Danielle Collins. Photo: Getty

Kenin, who won the Australian Open at the start of the year and then reached the fourth round at the U.S. Open last month, has now won a tour-leading 15 matches at majors this year.

Collins, who had won a rain-delayed three-set quarter-final against Ons Jabeur the previous day, left the court for a medical time out while trailing Kenin 4-0 in the third set.

Two-time Wimbledon champion Kvitova normally dictates play with her big serve and forehand but she double faulted multiple times when she being broken twice in the second set by German Siegemund.

Yet it wasn’t the seventh-seeded Czech, yet to drop a set in her five matches at this year’s tournament, who made the costliest double. That indignity befell Siegemund, who served one up on Kvitova’s second match point.

The German also needed a medical time out to have her lower back treated after dropping serve to give Kvitova a 3-2 lead in the second set.

It was another emotional occasion for Kvitova, who is getting ever closer to her first grand slam title since she suffered damage to ligaments and tendons in her playing left hand when fighting off an intruder in 2016.

Kvitova, who will be playing her first French Open semi-final since 2012, the year she lost to eventual winner Maria Sharapova, said: “Eight years ago I was young, I already won my Wimbledon title (in 2011) and I was kind of the favourite.

“I couldn’t imagine that I can be in the semi-final of a grand slam and final of the Australian Open even before. I’m really glad in the last couple of years I improved my results. I’m proud of this, and I hope this journey, it will not end yet.”

-AAP