Auger-Aliassime improves movement, demeanor under Toni Nadal guidance at US Open

WATCH: Auger-Aliassime foreshadowed his US Open semifinal run with impressive results in Cincinnati.

The 21-year-old Canadian Félix Auger-Aliassime's gained a lot of Grand Slam experience in recent weeks—both on the court and in his box.

Ranked a career-high of No. 15, he's reached the semifinals of the US Open, his first at a Slam, and also got to the quarterfinals of Wimbledon. But he wants to get even further, and now has an experienced hand to help him.

Having been coached by Frederic Fontang for several years, he's added Toni Nadal, Rafael Nadal's uncle and former coach, to his team. Rafael Nadal has won 20 Grand Slams, most of them with “Uncle Toni” in his box.

The group has established good communication since starting together during the clay season, says Auger-Aliassime, and it helps that Toni Nadal speaks French.

“I think it was a good decision," Auger-Aliassime told press. "He's helped me improve maybe the consistency of my game, the quality of my movement, my focus. Mainly the big thing is the belief and the confidence that he brings to myself and everybody involved in my team.

"I think on one part you have Frederic, my main coach, I would say has been with me since I'm very young, that knows me in every aspect of myself and my game. He has the long-term vision for me.

"You have Toni that has been in the places that we want to go one day, winning these big tournaments, being No. 1 in the world. He brings that belief that this is something we can achieve if we do the right things, work in the right direction.”

The former top junior has been considered one of the best up-and-comers on tour for a while, but his climb had slowed until the second half of this season.

Auger-Aliassime trained at Nadal's academy during the offseason, getting to know Toni, and then six months ago asked him to join his team.

"It’s been good to work with him. He's bringing a lot of instant feedback, always pushing to do things a little bit better, but also telling me when things are good, when they're in the right direction. It's been great work. Every time I try to bring a lot of focus, intensity into the practices. It's been good. I think it's paying off," said Auger-Aliassime.

"Toni and I sometimes talk about what I could do better, what I can still improve."

According to Toni, movement and nerves are the biggest areas.

"I told him that despite being a great athlete, he had to move more, because he played rather static. I also advised him to be calmer in important moments. The level he has shown here is quite high," said Toni, speaking to Marca. "He has to improve a little and he will be almost there, competing with the best players."

Following a straightforward win by retirement from Spanish teen Carlos Alcaraz, Auger-Aliassime plays No. 2 seed Daniil Medvedev in the semifinals.