Novak Djokovic survives deja vu scare after accidentally hitting line judge during French Open win over Karen Khachanov

World No 1 was disqualified from the recent US Open for hitting a line judge in anger but faced no action in Paris after accidentally repeating the incident during a point in his fourth-round victory

Novak Djokovic apologises to a line judge after striking him with the ball during a point at the French Open (AP)

Novak Djokovic had flashbacks to his dramatic US Open exit as he booked his place in the French Open quarter-final.

The world number one was sensationally disqualified in New York last month after he hit a ball in frustration that struck a line judge in the throat during his fourth-round match with Spaniard Pablo Carreno-Busta.

Djokovic again hit a line judge in his fourth-round win over Russian Karen Khachanov at Roland Garros, but as it was during a point he faced no action as he was able to complete a 6-4, 6-2, 6-3 victory.

The Serb was only able to get a frame on a wide serve from Khachanov in the third set and the ball deflected into the head of the service line judge.

"My gosh, it was very awkward deja vu," said Djokovic. "I'm actually trying to find the linesperson and see if he's OK because I saw he had a little bit of a bruise, like redness, in that place in the head where the ball hit him.

"I hope he's fine. I mean, he definitely dealt with it in a very strong and brave way. But it was a hit because I was very close.

"Obviously because of what happened in New York, people I guess are going to make the story out of this. It has happened to me and to many other players in the last 15 years that I've been on the tour.

"I've seen it a lot when the ball ricochets from the racquet and the frame, hits someone in the stands, or someone that is close to you or a line umpire.

"Yeah, it was a very awkward situation, obviously."

That was the biggest drama Djokovic has faced during the opening four rounds of the tournament in Paris as he has yet to drop a set and will be Rafael Nadal's main rival for the title come Sunday.

That next match sees him reunited with Carreno-Busta, a straight-sets winner over Daniel Altmaier - a strange coincidence given Djokovic's fright with the line judge in this match.

While Djokovic is a regular at this stage of the French Open, Stefanos Tsitsipas is here for the first time after he dispatched Grigor Dimitrov in straight sets.

The Greek, seeded number six, will now meet Andrey Rublev in the last out and he knows his tournament is about to get a lot tougher.

"It's going to be a difficult challenge. I'm not expecting things to get easier from this point, for sure," he said.

"Every single round is going to be more difficult than the previous one. Doesn't mean if things are this way right now they are going to be a different way later or tomorrow or the day after tomorrow. I keep learning every day.

"I think applying that to my game as much as possible, being responsible, being aware of all my choices and the decisions on the court."

Rublev has never been past the first round at Roland Garros until this year but backed up his run to the quarter-finals at the US Open with another one here.

"I mean, of course I feel great. I feel great with my performance for last couple of weeks, in general with my season. I'm really grateful," he said after a four-set win over Marton Fucsovics.

"I mean, like every player, I don't think that I did something more than others. I think physical-wise I feel like the same like all the rest because we play the same matches."

PA