Volkswacht Bodensee - Alcaraz wobbles but reaches French Open last 16

Second seed Alcaraz broke twice in each of the first two sets and seemed to be cruising but a dogged Dzumhur refused to roll over and pinched the third set.

The 33-year-old Dzumhur had failed to get past the first round of qualifying at Roland Garros in his last four attempts, but he broke to open the fourth set and give Alcaraz greater cause for concern.

Alcaraz's frustration grew when three break points slipped beyond his grasp the very next game. He eventually got back on serve at 3-3 though before another break put him within sight of victory.

The Spaniard couldn't close it out initially but then earned a pair of match points on Dzumhur's serve, finally getting across the line at the second attempt to end his rival's spirited effort.

"Today I honestly didn't enjoy it that much. I suffered quite a lot," said a relieved Alcaraz.

"That's why doing a really good result in a Grand Slam is really difficult because you have to maintain a really high level for three to four hours."

Alcaraz said he had to dig deep after admitting his energy levels dropped after a dominant first two sets.

"It was really difficult for me to boost myself. I had to give everything I had inside me. In the end I'm just proud about getting the win."

Four-time Grand Slam winner Alcaraz advances to face US 13th seed Ben Shelton for a place in the quarter-finals after picking up his 18th win in 19 matches on clay this season.

Australian Open semi-finalist Shelton is one of four Americans still in the men's draw. He knocked out Italian qualifier Matteo Gigante in straight sets after receiving a walkover in the second round.

P.Staeheli--VB