Novak Djokovic plays a backhand during his men's singles quarterfinal match against Pablo Carreno Busta at the 2020 French Open on Wednesday at Roland Garros in Paris. Photo: VCG

Novak Djokovic said he was "feeling OK" after overcoming neck and shoulder troubles to defeat Pablo Carreno Busta on Wednesday and set up a French Open semifinal showdown with Stefanos Tsitsipas.

Djokovic beat Spanish 17th seed Carreno Busta 4-6, 6-2, 6-3, 6-4 to reach the last four of a major for the 38th time as he chases a second French Open and 18th Grand Slam title.

However, the world No.1 required treatment on his upper left arm after dropping his first set of the tournament on a chilly autumn evening in Paris.

"I definitely didn't feel great coming onto the court today, a few things happened in the warm-up," said Djokovic.

"I had some neck issues and some shoulder issues. I don't really want to get too much into it.

"I'm feeling OK, I'm still in the tournament so I don't want to reveal too much. As the match went on, I felt better, didn't feel as much pain."

The Serb now sits two wins away from becoming the first man in half a century - and only the third in history - to win all four Slams twice.

His only defeat in 37 matches this year came to Carreno Busta following his disqualification at the US Open for an angry swipe of a ball which hit a female line judge squarely in the throat.

Djokovic again looked vulnerable against Carreno Busta, who twice had chances to break in the second set but could not capitalize, instead losing his own serve on two occasions.

"For a set and a half he was the better player, dictating the play," said Djokovic.

The Serb unleashed a primal roar having fended off two break points in the first game of the third set and appeared in control at 3-0 until Carreno Busta clawed back to 3-all.

But the top seed reclaimed the initiative with another break at 4-3 on his way to taking the third set.

Djokovic grew increasingly animated when he missed out a string of break points early in the fourth set, but he eventually landed the decisive blow in the seventh game when Carreno Busta pushed a forehand wide. 

"It was really anybody's game. It was so close. He had his chances. I had my chances. It was a very even match even though it was three sets to one," said Djokovic.

Tsitsipas gets revenge 

Tsitsipas made his second Grand Slam semifinal with a straight-set victory over 13th seed Andrey Rublev, avenging last month's loss to the Russian in the Hamburg final.

The Greek fifth seed downed Rublev 7-5, 6-2, 6-3 to match his breakout run at the 2019 Australian Open.

"I'm expecting since a young age to potentially triumph at these Grand Slams. I'm happy that I'm able to be in a position where I am today," said Tsitsipas. "I'm chasing something spectacular."

"Despite not having a good start and being a break down, I remembered what a big fighter I am," he added.

"It's also about fighting and trying to find solutions in difficult moments. I managed to put my brain to work."

Tsitsipas, 22, has now won 15 successive sets at the tournament having been two sets down to Jaume Munar in the opening round.

However, that streak looked in peril when Rublev, also making his first French Open quarterfinal appearance, served for the opening set at 5-4.

A loose game from Rublev allowed Tsitsipas to recover and he rattled off four points in a row to take the lead.

Tsitsipas, last year's ATP Finals champion, dominated the second set to leave Rublev on the brink, profiting from a favorable net cord to break at 3-2 after carving the opening following a 28-shot rally.

Only Djokovic has won more than Rublev's three titles in 2020, but the world No.15 was powerless to stop a supreme Tsitsipas who closed out victory inside two hours.

Tsitsipas crunched 35 winners and made just 17 unforced ­errors. He holds a 2-3 record against Djokovic going into Friday's ­encounter.

"I expect a really tough match, a tough challenge for both of us. This is what you expect in the semifinals of a Grand Slam," said Djokovic.

"He's been playing the tennis of his life in the last 12 months."