Carlos Alcaraz surprised himself with the level of performance he was able to produce in his win over Andrey Rublev at the ATP Finals on Tuesday.
Alcaraz emerged a 6-3 7-6 (10-8) victor against the Russian in his second match of the tournament, keeping his hopes of advancing to the next round in Turin alive.
The Spaniard fell to defeat in his opening game against Casper Ruud, citing a stomach issue that left him feeling unwell before and during that match.
But the world number three looked back to his brilliant best against Rublev, claiming the first set in 37 minutes before edging a thrilling tie-break in the second.
"Yes, I surprised myself a lot," Alcaraz said shortly after the victory.
"The way I played today from the baseline, I was really calm and tried to just focus on my game and what I had to do - forget that I'm not really feeling well.
"Once you step on the court, you have to forget everything you're struggling with outside the court."
Alcaraz, though, said he was still not feeling 100% ahead of facing Alexander Zverev, who is in action against Ruud later on Tuesday.
It will be the pair's first meeting since the Spaniard's triumph in the French Open final in June, but Zverev has not let that defeat ruin a fine season.
His own opening win over Rublev was his ATP Tour-leading 67th win of the campaign, with only Jannik Sinner matching the German for victories this year.
"I could be better, healthier. I'm just trying to step on the court and play good tennis, try not to think about my issues right now," Alcaraz said.
"I've been struggling the last week and that's going to be the case over the next day too, for sure.
"Zverev is playing great tennis. He is one of the toughest players in the world right now, that's for sure.
"I will try to play good tennis and enjoy the same way I did today. Then let's see."