The 26-year-old Canadian star appeared to hurt his knee in the fourth game of the match before he lost his serve to fall 1-3 behind.

Auger-Aliassime tried to continue, but he pulled the plug with Ruud leading 5-2, 15-15 in the first set after he was heard telling his team: "it hurts too much."

The world No 6's last 16 exit at the Masters 1000 tournament in Shanghai is a blow to his hopes of qualifying for the ATP Finals in Turin.

Auger-Aliassime, who was a semi-finalist at the 2025 ATP Finals, is currently 15th in the Race To Turin - 415 points behind Alex de Minaur, who currently occupies the eighth and final qualification place.

Following his retirement against world No 24 Ruud, Auger-Aliassime described the pain in his knee as "too intense" for him to keep playing.

"I felt something in my knee on a point at 2-1. I tried to keep playing, but the pain was too intense," Auger-Aliassime was quoted as saying by L'Equipe.

"I'm going home now for tests, and I hope it's nothing serious and that I can play in the next tournament.

"I'm registered for Brussels, but I have to go home for examinations and find out what the next steps will be for me."

Auger-Aliassime is scheduled to defend his title at the European Open - an ATP 250 tournament in Brussels - next week.

In his press conference, Ruud spoke about Auger-Aliassime's injury.

"Honestly, I mean, there's not that much to say. It was very unfortunate for him. It seemed to me that he maybe twisted his knee in the fourth game of the match," said the three-time Grand Slam finalist.

"He came to the net, and I kind of, I didn't see it a hundred percent because I'm focusing on the ball, but it looked like he kind of stumbled a bit with a wrong step. From that moment, it seemed like he was in a lot of pain, which is very unfortunate.

"I'm very sorry for him, because it's a big match for both of us. I know what kind of player he is, what kind of person he is; very nice person, so you don't wish this for anybody. I hope he has a speedy recovery."

READ MORE: Aryna Sabalenka stunned by Ann Li in Wuhan Open second-round as poor run continues

LAHIRU UDARA

Lahiru Udara replaces injured Pathum Nissanka in Sri Lanka's Test squad

Editors Pick