The fourth seed never looked likely against veteran Kaia Kenepi, who swept past Kenin in a 6-3 6-2 second-round rout on Thursday.

"Since last year, I won, then obviously I feel like everyone is kind of expecting me to do that. It's obviously tough," Kenin said.

"I couldn't close it out ... I felt like I obviously wasn't there. My head wasn't there.

"Obviously I'm not going to take any credit away from (Kanepi). She played really well at those good points.

"I had chances. I just couldn't take it. I obviously know why because, the nerves big-time got to me."

Kenin is the biggest domino to fall so far at Melbourne Park.

Beyond her Australian Open triumph, the 22-year-old also made last year's French Open final and was named WTA player of the year.

But she had a difficult start to summer, copping a straight-sets thumping from Garbine Muguruza in the Yarra Valley Classic, and was tested by Maddison Inglis in the first round.

"I couldn't really handle the pressure," Kenin said.

"I'm not obviously used to this, so right now I've just got to figure out how to play at that level that I played at (previously)."

An emotional Kenin said she needed to lift her form to regain a place among the grand slam contenders.

"I feel like everyone was always asking me ... 'do you see yourself getting there and winning again?' Obviously I said yes," she said.

"But with the way I'm playing - no."

Australian Associated Press