The ultimate test of Felix Auger-Aliassime’s improvement will come on Sunday in Paris, when he faces his coach’s nephew

WATCH: Before his fourth-rounder against Felix Auger-Aliassime, Rafael Nadal stopped by the Tennis Channel desk at Roland Garros

Felix Auger-Aliassime hit what may have been the shot of the tournament so far during his 7-6 (3), 7-6 (2), 7-5 third-round win over Filip Krajinovic at Roland Garros on Friday. Krajinovic had slid the ball almost parallel to the net, and just a few inches in front of it; it was a shot that appeared to have won him the point. Until Auger-Aliassime reached out and flicked a forehand in the opposite direction, even closer to the net, for a winner. The crowd at Court 14 stood, Krajinovic applauded, and Auger-Aliassime strutted back to the baseline and put his finger to his ear to tell everyone to roar just a little bit louder, please.

It was a rare moment of theatricality for the calm and collected Canadian. He probably felt like he deserved a chance to let loose and flash a smile, after the spring he’s had.

Auger-Aliassime’s results from early March to early May were as baffling as they were disappointing. After two straight successful Grand Slam performances, in New York and Melbourne, he had broken into the Top 10 and won his first final in nine tries, in Rotterdam. But just when it looked like he was ready to launch himself into the game’s highest echelon, he struggled to win any matches at all. Auger-Aliassime lost in the first round in Indian Wells and Miami, and coming to Roland Garros he was just 9-8 since the beginning of March. As a new star, Carlos Alcaraz, stepped into the spotlight, Auger-Aliassime sank out of sight. In the age of Carlitos, was there still a place for Felix?

“What we do is difficult,” the 21-year-old Auger-Aliassime said after one of those early losses, in Monte Carlo. “It’s difficult to maintain what I’ve been doing in the beginning of the year. Only a few players are able to do that. I’ll try to be one of those players in the future, but I still need to improve many things.

“This is the most difficult part of our sport. We lose very often.”

Fast forward a month, and Auger-Aliassime isn’t losing quite as often, or as early, as he was. He reached the quarterfinals in Rome and played an excellent, explosive match against Novak Djokovic, losing in a pair of close sets. He came back from two sets down in his opener in Paris, and beat a quality opponent in Krajinovic on Friday.

While it was his acutely angled winner that brought the crowd to its feet, it was his solidly aggressive play in the clutch moments at the end of each set that won him the match. In the two tiebreakers, which essentially decided the result, Auger-Aliassime served impeccably, returned aggressively, and took over the rallies with his forehand.

“I was serving really well,” FAA said. “First two sets I thought I was playing a little bit better, was hitting the ball really well with just a few unforced.”

Now the spotlight will swing back to Auger-Aliassime, when he goes up against Rafael Nadal in the fourth round. For the last 15 months, Auger Aliassime has been working with Toni Nadal, Rafa’s uncle and longtime coach. (FAA also travels with his own longtime coach, Frederic Fontang.) This will be the first meeting between Rafa and FAA during that time. Auger-Aliassime says Toni will view the match from a “neutral place,” and probably won’t coach against his nephew.

“I don’t know if I need insight on how Rafa plays, to be honest; I think we all know what he does well,” FAA said with a smile on Friday.

“It’s up to me, at the end of the day, when I come on the court to try to find solutions.”

Still, the work that Toni and Auger-Aliassime have done could pay dividends on Sunday.

“We worked a lot on my movement on the court, my intensity of footwork, the way I can now move,” Auger-Aliassime said. “In and out of the court, I can defend better, and I think I’m more precise with what I do.”

According to Auger-Aliassime, it sounds as if Toni is as opinionated as he always was with Rafa.

“Toni, he’s a guy who—how can I say?—gives you a lot of feedback when you’re practicing,” Auger-Aliassime said. “If I miss a point, he’s going to tell me you could do this or that, or watch the balls more, or try this, technically speaking.

“He’s given me confidence that I can reach the best levels if I improve a number of points, if I’m a more all-around player.”

Auger-Aliassime seems to be reaching upward again. The ultimate test of Toni’s coaching, and FAA’s improvement, will come on Sunday.