Fifth seed Australian Samantha Stosur on Saturday lost to Czech's Petra Kvitova 7-6(5), 6-3 in the third round of the Australian Open.

Kvitova won the first set in a tiebreak and then raced through the second set to book a clash with Italian Flavia Pennetta in the round of 16.

Stosur has never gone beyond the fourth round of the home ground Grand Slam in nine attempts.