INDIAN WELLS, Calif.—Rafael Nadal sees high potential in Alexander Zverev, saying the German teenager could get to the top of the game.

The two played each other for the first time in the fourth round of Indian Wells, with Nadal winning a fierce and sometimes fiery encounter, 6-7 (8), 6-0, 7-5.

But the Spaniard had talked up his opponent even before the match.

Calling Zverev a "possible future No. 1," Nadal said, "He's an amazing player. He has all the shots. Very good physical performance. Tall, good serve, first and second; great shots from the baseline, forehand and backhand.

"He has everything to become [a] big star, and he's playing well.”

The 18-year-old is set to leapfrog his career-high No. 56 ranking with his showing in Indian Wells.

Told that Tomas Berdych also said something similar, Zverev gave a measured response.

"We have been really good friends with him,” Zverev said. “We practice quite a lot. He gives me quite good advice, as well. So yeah, if someone like him says something like that, it's always a big honor. I know that I still have a lot of work ahead of me. As I said, I think it's a long way."

Nadal could play Novak Djokovic in the semifinals.