Third seed Victoria Azarenka overcame a shaky first set to scrape through to the semi-finals of the Australian Open.

The Belarusian defeated Poland’s Agnieszka Radwanska in just over two hours, labouring to a 6-7 (0-7) 6-0 6-2 victory.

It was her second win over the eighth seed in two weeks after beating her in the semi-finals of the Sydney International.

The opening set was littered with service breaks from both players, eventually moving to a tiebreak which Radwanska ripped through without losing a point.

But the match turned completely in the second set as Azarenka collected service breaks with ease to level the match at one set all.

She held three match points in the final game and while Radwanska managed to save two, a smash into an open court sealed the match for the Belarusian player.

“We just cannot play two sets, we have to push each other to the limit and keep running around,” Azarenka said later.

She now meets the winner of the quarter-final between World No.1 Caroline Wozniacki and defending champion Kim Clijsters.

“It’s going to be a great match and high quality tennis – either one would be a great opponent,” Azarenka said.