'It hurts': World No.8 'punching bag' forced to retire after trying to play through the pain

Men's world No.8 Felix Auger-Aliassime says he didn't want to be a "punching bag" after retiring hurt from his opening match at the Australian Open.

The 25-year-old Canadian star won the first set against Nuno Borges but lost the next two, and was clearly hampered by an injury before attempting to start the fourth set but then giving up.

He succumbed to the injury, which he later revealed was simply cramp.

FOLLOW LIVE: Australian Open day two coverage

READ MORE: 'Bananas' crowd smashes record, catches boss off guard

READ MORE:'Calm down': Smith booed by fans as 'frustration' boils over

When speaking to media post-match, Auger-Aliassime was struggling to put a finger on what went wrong.

"I'm OK, I just started cramping at the beginning of that third set, and it became very difficult to be competitive at this level," he said.

"I tried for a set, but it wasn't possible.

"I don't have all the answers now. I'm trying to be very professional in everything I do, I love the sport and I love to play, so I try to do everything I can in my control to get ready.

"It hurts even more... I'm not totally finding the reasons why this is happening. It wasn't happening in the past.

"I can't recall ever (cramping) this early in a tournament, this early in a match.

Watch the Australian Open live & free on the 9Network & 9Now. Stan Sport is the only place to watch every match ad-free, live & on demand with centre court in 4K.

"I knew it wasn't heading in the right direction, I don't like to be on the court that way... I don't want to be just standing there like a punching bag. There's no point to carry on."

Auger-Aliassime was hampered by illness during the United Cup earlier this month but says he's unsure if Monday's issue is related to that.

World No.46 Borges advances to the second round.

"Not the way he would have wanted to win," Colin Fleming said on Nine.

"It's horrible, you never want to see a player struggling with injury.

"There was no way it could have continued ... he couldn't compete, he couldn't move."

At the time of his retirement, Auger-Aliassime was the highest seed on the men's side to be bundled out of the Australian Open.

Flavio Cobolli, the 20th seed, was beaten on Monday.