Petra Kvitova into Australian quarters

Petra Kvitova has booked her place in the Australian Open quarter-finals with a straight-sets victory over Ana Ivanovic.

The Serbian hung in for the opening exchanges, but she soon became frustrated by Kvitova's power as the Czech took the first set 6-2.

It was much the same in the second as Kvitova found a break of serve at 2-2. However, with her opponent looking as if she was on the way to a comfortable victory, Ivanovic broke back at 4-5 before taking the set to a tie-break.

Despite her endeavour, Ivanovic was brushed aside in the tie-break as the world number two closed out the match 7-2.

The 21-year-old will face either Italy's Sara Errani or China's Jie Zheng in the last eight.