World No. 3 Carlos Alcaraz looked like himself again on Wednesday, defeating Andrey Rublev 6-3, 7-6 (8) to improve to 1-1 at the Nitto ATP Finals in Turin, Italy.

Alcaraz, the No. 3 seed, battled a stomach issue during his 6-1, 7-5 loss to sixth-seeded Norwegian Casper Ruud during round-robin play on Monday.

The Spaniard came back and made fairly quick work of the eighth-seeded Rublev, dispatching the Russian in one hour and 36 minutes.

“I surprised myself,” said Alcaraz, who wore a pink nasal strip during the match to help him breathe easier.

“The way that I played today from the baseline, with my serve. I was really calm. I just tried to be focused on my game and what I had to do and forget about that I’m not feeling well and that I’m sick.”

Alcaraz won 84.1 percent (37 of 44) of his first-serve points, held a commanding 33-14 advantage in winners and never faced break point.

He waltzed through the first set before having to save a pair of set points during a second-set tiebreaker to improve to 2-1 in his career against Rublev.

Alcaraz will meet No. 2 seed and two-time ATP champion Alexander Zverev on Friday as both vie for a spot in the semifinals. Even if he still isn’t 100 percent healthy, Alcaraz knows how to lock in mentally as the stakes increase.

“Once you step on the court, you have to forget everything, your struggles outside the court, and you try to put your focus on hitting a good forehand, a good backhand and making good tactics against the opponent,” he said. Zverev beat Rublev 6-4, 6-4 on Monday before taking care of Ruud 7-6 (3), 6-3 on Wednesday.

The German racked up 11 aces to Ruud’s three and won 87.2 percent (41 of 47) of his first-serve points.

He also had a 28-13 advantage over Ruud in winners. Zverev secured the match’s only break point in the second set and pulled away to win in one hour and 26 minutes.

Unwell Carlos Alcaraz unlikely to be at 100% for Rublev match at ATP Finals, says coach

“I think it was a very good match actually from both of us,” Zverev said. “I’m happy to win today, but it was very, very close.”

Ruud and Rublev will square off on Friday to conclude round-robin play in the John Newcombe Group.

The Ilie Nastase Group, which wraps up Thursday, features World No. 1 Jannik Sinner of Italy, Daniil Medvedev of Russia, Alex de Minaur of Australia and Taylor Fritz.