Dominic Thiem taking inspiration from Rafael Nadal as tennis "must catch up" with Carlos Alcaraz

WATCH: Dominic Thiem wins in Gijon

Gaining momentum on the comeback trail, Dominic Thiem is through to the semifinals of the Gijon Open in Spain, and already surveying the top of the men's game.

The 29-year-old Austrian, who won the 2020 US Open, says new No.1 Carlos Alcaraz is "about to change tennis,” pointing to the 19-year-old's aggressive style of play while capturing the most recent US Open.

“He is about to change tennis, because in New York, no matter how long the matches went on, he was there the whole time, playing offense, going to the net and contesting every point with no fear. And I think this is new," Thiem told AS in an interview. Nobody did that before. We must catch up.”

In his breakthrough season, Alcaraz has also won ATP events in Rio de Janeiro, Miami, Barcelona and Madrid.

''He already has a unique career. He is the youngest No. 1 in history and winner of the US Open, as a teenager, [it's] exceptional,” Thiem said.

But as Thiem attempts to come back from wrist surgery that kept him off the tour for several months, he's looking to another Spaniard, 22-time Grand Slam champion Rafael Nadal, who is at No. 2 and won two Grand Slams this season despite significant injury problems in recent seasons.

"He is probably the best role model for this experience, since he did it not only once, but four or five times to come back from a long injury of six months or even more. And his level was always incredible," said Thiem. "So it's a great inspiration."

Thiem has won 17 titles and has been ranked No. 3, but is currently ranked No. 165 more than six months into his comeback. Still, he's convinced he's got the ability to get back towards the top of the game again, saying his forehand is getting back to where it was and his backhand has actually improved.

"I do have the feeling that I'm once again capable of fighting for the big titles, for the Slams, of beating anybody," he said. "Otherwise, I wouldn't feel like working hard. I hope next year, I can do it."

But his current goals are much smaller.

"I want to finish the year in the Top 100," he said.

Thiem is playing using his injury-protected ranking in Gijon, and has defeated Joao Sousa, Marcos Giron and Francisco Cerundolo thus far.