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The second seed was pushed the distance by World No. 56 Damir Dzumhur, eventually prevailing 6-1, 2-6, 6-3 in a clash that veered far from straightforward after a lightning-fast start.

"It was just a rollercoaster," Alcaraz said. "Lots of good feelings, bad feelings, back to the good ones. All I can say is I am happy to get the win at the end and just have another chance to be better. 

"I will try tomorrow to have my confidence back because today it was a little bit tricky. Damir plays really smart tennis, which I have to be focused and ready for that. I have a rest day tomorrrow, to give myself the confidence back and hopefully be better in the next round."

Alcaraz looked primed to match his rival Sinner’s efficiency, racing through the first set in just 28 minutes. But while the defending champion Sinner barely hit a bump against Daniel Elahi Galan, Alcaraz found himself off course in the second set.

With errors creeping in and his intensity dipping, the World No. 2 opened the door for a surging Dzumhur, who began charging the net and taking control of the rallies to level. Alcaraz crucially regrouped in the decider, finding just enough firepower and precision to steady the ship and close out the match after one hour and 41 minutes.

The Spaniard has now won his past 12 ATP Masters 1000 matches, but will be concerned by his second-set lapse in his first match on a hard court since his opening-round loss in Miami in March. Alcaraz committed 44 unforced errors against Dzumhur and failed to save any of the three break points he faced.

"Here it is difficult to play such great tennis," Alcaraz said. "The ball flies a lot, goes super fast. You have to be ready to be in a good position for each shot and that is really difficult to do. 

"You have to know there will be a few points and games in the match when you won't feel good, so you have to maintain the positive thoughts in the right way... It is a relief about getting the win."

Alcaraz was competing for the first time since he lost to Sinner in the Wimbledon final. Having both qualified for the Nitto ATP Finals, Sinner and Alcaraz will compete in a thrilling battle for ATP Year-End No. 1 honours over the remaining months of the year. Alcaraz currently holds a 1,500-point lead over Sinner in the ATP Live Race To Turin.

The World No. 2 in the 52-week ATP Rankings, Alcaraz has clinched a Tour-leading five titles in 2025, including Masters 1000 crowns in Monte-Carlo and Rome. The 22 year-old’s best result in Ohio came in 2023, when he lost in a three-set final thriller against Novak Djokovic. Alcaraz will next meet Tallon Griekspoor or Hamad Medjedovic.