Angelique Kerber plans to banish the memories of her shock Sydney International defeat to Daria Kasatkina and regain the "positive energy" she generated last year in time for the Australian Open.

The world number one was beaten 7-6 (7-5) 6-2 by unseeded Russian teenager Kasatkina in the second round of her last tournament before the opening major of the year starts next week.

Kerber - given a bye into round two - looked a shadow of the player who won her first two majors in 2016 en route to replacing Serena Williams at the top of the rankings, racking up the unforced errors and failing to hold serve five times.

It has been an unconvincing start to the season by the German, who lost her second match of the tournament at the Brisbane International to Elina Svitolina last week.

But the powerful left-hander is determined to ensure she is firing on all cylinders in Melbourne rather than dwell on her failure this week.

"I made too many mistakes and I was not actually feeling the ball, because the balls are flying here a little bit different than in Brisbane," she said.

"So it was not so easy, but I will try to forget the match as soon as I can.

"I will go in the next few days to Melbourne, and I will try to get ready there, trying to get the positive energy from last year."