Carlos Alcaraz won only three games in his previous meeting against Rafa Nadal but after pushing the 21-times major winner to the brink on Saturday, the teenaged Spaniard will leave California assured he belongs at the top tier of men's tennis.

The 18-year-old Alcaraz lost 6-1 6-2 in just 78 minutes against his fellow Spaniard when they met on clay at Madrid last year but forced Nadal to raise his level during a three hour and 12 minute slugfest in the semi-finals of Indian Wells.

Nadal, 35, prevailed 6-4 4-6 6-3 after an engrossing contest amid strong winds but Alcaraz showed why he is considered the future champion of the sport.

“I think I’m more mature than last year,” Alcaraz told reporters.

“Now I know how to play against these kind of players. I played a lot of matches against great players. Second time against Rafa. I feel like I'm part of that level.

“I think I'm going to play against Rafa or the best players this year a lot. Now I think that I'm ready for the others.”

The Spaniard became the youngest to clinch an ATP 500 level title last month at Rio de Janeiro, two years after winning his first tour-level match at the same tournament. He’s already broken into the top-20 of the men's rankings.

Alcaraz said in some moments he felt he could beat Nadal on Saturday and promised to be more calm and relaxed on court the next time he met his compatriot.

“Rafa has thousand lives. If he’s down, he's able to play at a great level in the tough moments,” Alcaraz said. “Yeah, I thought I could win in the third.”

Nadal, who is unbeaten in 2022 and has now won 20 matches on the trot in his best start to a season, said his semi-final win against Alcaraz was his best of the tournament in terms of his level.

He had no doubt that Alcaraz will rule the sport in future.

“I think he has all the ingredients to become an amazing champion,” Nadal said. “The energy, the speed on the runs. The amount of passion and determination that he has to become a great champion. Yeah, that’s what I see in him.

“Looks like he’s humble enough to work hard and to understand that we, the tennis players, if we want to be great champions, the only way is to keep improving during all our careers. That’s what I tried. I really believe that he’s doing that.”