Carlos Alcaraz feels it is a matter of time before he becomes a really good player on indoor courts. The Spaniard admitted he doesn’t have a lot of experience of playing on indoor courts and feels a lot of players are better than him on such courts.

Alcaraz suffered a 1-6, 5-7 loss against Casper Ruud in his opening match of the Nitto ATP Finals on Monday. The Spaniard was leading by 5-2 in the second set but lost five games on the trot. The youngster revealed he was feeling discomfort in his stomach.

“I didn’t feel well on court,” Alcaraz said. “A few days before coming here, I got sick at home. … This morning, I feel uncomfortable in the stomach.”

“I have no experience playing on indoor courts,” Alcaraz said. “I’ll be a really good player on indoor courts, I’m sure about it. But I think it’s about time, about getting experience. … A lot of players are better than me on indoor court.”

Meanwhile, Ruud feels a win against Carlos Alcaraz will definitely add a shot in his arm as he hasn’t been at his absolute best.

“I’m not full of confidence,” Ruud said. “A match like today might be able to change it.”

On the other hand, Alcaraz admitted tight scheduling on the tour hasn’t helped him stay fresh.

“I’m tired mentally,” Alcaraz said. “Obviously a lot of matches, really tight schedule, really demanding year with not too many days off.”

Meanwhile, Alexander Zverev began his bid for a third ATP Finals title by beating Andrey Rublev 6-4, 6-4. The Russian admitted that the German was too strong on his serve.

“He served wide 220 (kph) on the deuce side,” Rublev said. “Normally everybody serves slice and it’s 190. He find(s) a way to serve 220 wide on the deuce side. It’s not easy.

“Even if you catch the direction, when the flat serve comes 227, slice serve comes 219, 215, it’s tough to just see the ball.”

Alcaraz will next take on Andrey Rublev on Wednesday in Turin.