US Open champion Emma Raducanu has lamented a poorly-timed and even more poorly-located debilitating blister after making a shock second-round exit from the Australian Open.

Teen sensation Raducanu became the first qualifier to win a grand slam when she triumphed at Flushing Meadows without dropping a set last year but saw her debut Melbourne Park campaign end with a 6-4 4-6 6-3 loss to Danka Kovinic.

She was plagued throughout the match by the nasty blister in the crease of her racquet-wielding right hand, but said she'd been unwilling to retire and was proud she fought it out.

"I was struggling with my hand before the match," Raducanu said.

"There were some people in my team that maybe didn't want me to play, but I wanted to go out there and fight through it, see how far I could get.

"I fought so hard just to come out to Australia and play here, and I didn't want to go out like that. So I just left it all out on the court."

The 19-year-old frequently had to default to a sliced forehand and required treatment throughout the match.

"(You wonder) how can a small thing like a blister cause so much pain and aggravation? But it's just the position of it. It's right in the crease, it's so deep," she said.

"I just can't grip the racquet. Like every time I hit, make contact with the ball, it would create an impact.

"Or say I hit one slightly off centre and the racquet moves a bit in my hand, it's just like even more friction and it rips again.

"So it's very painful, like every single shot you really hit."

Raducanu, who tested positive for COVID-19 in December, said she'd struggled with blisters since arriving in Australia, as her hands had "got pretty soft" after not playing for 21 days.

She revealed avoided hitting forehands and serves in practice this week to avoid aggravating the blister, instead sticking to backhands.

"This particular (blister) has been with me for about five days," she said.

"I've been trying to tape it for every practice and it would harden and dry out but then once I would play again, another layer would just keep ripping off so it ended up being pretty deep."

The victory was a delightful change of fortunes for world No.97 Kovinic, who last year copped a 6-0 6-0 first-round thrashing from world No.1 Ash Barty, and had never previously reached the third round of a slam.

She will next play 2018 finalist and former world No.1 Simona Halep.