CINCINNATI (AFP) — Carlos Alcaraz had to fight his way out of a second-set slump to escape with a 6-1, 2-5, 6-3 victory over Damir Dzumhur in his opening match at the ATP-WTA Cincinnati Open on Sunday.

The Spaniard, playing his first tournament since a runner-up finish to Jannik Sinner at Wimbledon, raced through the first set but completely lost his way in the second, dropping his serve twice against the 33-year-old Bosnian.

But he regained his intensity — and cut down his errors, in the third. Alcaraz fired his seventh ace to set up a match point and advanced to the third round seconds later as his opponent fired wide.

Alcaraz, seeded second, claimed his 12th consecutive match at the Masters 1000 level after titles in Monte Carlo and Rome.

"It was a relief to get this win," Alcaraz said after committing 44 unforced errors.

"It was a rollercoaster of good feelings and bad feelings.”

"I was happy to get the win in the end. I know that I have chances to do better. I will use the day off tomorrow to get my confidence back. It was a little tricky, I need to play smart tennis."

Alcaraz, runner-up in Cincy in 2023, next faces Serbian Hamad Medjedovic, a 6-4, 7-6 (7/3) winner over Dutchman Tallon Griekspoor.

American Ben Shelton, coming off his first Masters 1000 title in Toronto, eased through his opener 6-3, 3-1 as opponent Camilo Ugo Carabelli was unable to continue because of a right knee problem.

The Argentine who beat Kei Nishikori in the first round, pulled up short after the first point of the third game of the second set, gripping his knee.

With a tournament supervisor translating from Spanish, the South American then took a medical time out. Once back, he only lasted three more points.

Shelton had less than an hour on court, something of a favor after a draining Toronto tournament which only ended on Thursday.

"It's not easy to play a couple of days after winning any title," he said.

"I feel for Camilo. I hope he has a quick recovery.”

"I wanted to compete and be a warrior this week — see what I could do," said Shelton, adding when asked about tape on his right thigh that he has "a few muscle things."

"The legs take a lot of the force," he said.

Sixth seed Alex de Minaur, the Washington champion and a Toronto quarterfinalist last week, was bounced by American Reilly Opelka 7-6 (8/6), 6-4, who crushed 14 aces and saved all seven break points he faced.

Australian Adam Walton upset slumping former number one and 2019 Cincy champion Daniil Medvedev 6-7 (0/7), 6-4, 6-1 for the first top 50 win of his career.

Spanish veteran Roberto Bautista Agut dismissed Briton Cam Norrie 6-4, 6-3 while number nine seed Andrey Rublev beat American Learner Tien 7-6 (7/4), 6-3.

In women's action, second-seeded French Open champion Coco Gauff battled through a tough first set to beat China's Wang Xinyu 6-3, 6-2.

Gauff, who lifted the trophy in Cincinnati in 2023 and went on to claim her first Grand Slam title at the US Open that year, grinded through a first set marred by five service breaks.