PARIS (Reuters) -Defending champion Carlos Alcaraz suffered a mid-match stumble but recovered just in time to beat Bosnian veteran Damir Dzumhur in four sets on Friday and move into the French Open fourth round.

The world number two was supreme in the opening two sets but then inexplicably took his foot off the gas before bouncing back from 3-1 down in the fourth set to subdue his 33-year-old opponent for a 6-1 6-3 4-6 6-4 victory.

"Today I didn't enjoy it that much. I suffered quite a lot today but happy to have played a good match with him," the Spaniard said.

"Doing a good Grand Slam is difficult, you have to play good tennis for three, four hours and maintain the focus. The first two sets were under control, playing great, feeling great."

"He then played more aggressively. I got down on my energy and it was difficult to push myself. I had to fight but in the end I am proud to get the win," Alcaraz said.

The Parisian crowd that had filled the Philippe Chatrier stadium in the hope of a lengthy and entertaining night session initially thought they had got the abridged version, with Alcaraz near flawless in the opening two sets.

The 22-year-old four-time Grand Slam champion pummelled the Bosnian into submission, breaking him twice to race through the first set in 27 minutes.

Dzumhur, looking to become the first Bosnian to reach the fourth round of a Grand Slam, had a break point at the start of the second set but was again quickly overrun as Alcaraz opened up a 3-1 lead.

His opponent tried to disrupt the Spaniard's power game with drop shots but to no avail as Alcaraz secured the second set on a Dzumhur double fault.

The Bosnian took a medical timeout for treatment to his groin, trailing 3-2 in the third set, and the tables turned after that.

He managed to bounce back, breaking Alcaraz and snatching the set, with the defending champion clearly rattled.

Another break put Alcaraz, who had two unforced errors in the first set but a staggering 20 in the third, firmly on the back foot with Dzumhur pulling 3-1 ahead in the fourth set.

Alcaraz restarted his engines just in time, reining him in and moving 5-3 up.

He finished the job with another break shortly after to set up a fourth round clash with American 13th seed Ben Shelton.

(Reporting by Karolos GrohmannEditing by Toby Davis)