A resurgent Ana Ivanovic shook off her girl-next-door image and revealed a delicious mean streak on Sunday as she dumped an injury-hampered Serena Williams from the Australian Open fourth round in one of her finest victories in years.

A one-slam wonder long derided as brittle in the clinches, the 26-year-old Serbian overhauled the favorite, 4-6, 6-3, 6-3, in a dazzling display of power hitting that left the Rod Laver Arena crowd thrilled and astonished in equal measure.

Restricted by a back injury and numbed with painkillers, top-ranked Williams struggled with her movement and was well off her best, but was given no quarter by Ivanovic, who attacked the American's serve with arrogance and closed out the match with barely a hint of nerves.

The greatest player of her generation, Williams has long traded on her aura and a CV boasting 17 Grand Slam titles, and 14th seed Ivanovic faced a battle to forget her opponent's fearsome reputation and her winless record against her.

"We all know what kind of champion she is," former world No. 1 Ivanovic told reporters after reaching the quarterfinals at Melbourne Park for the first time since 2008, when she eventually lost in the final to Maria Sharapova.

Having never won a set let alone a match against the American in their four previous career meetings, Ivanovic ended the American's 25-match winning streak that included last year's U.S. Open and a perfect end to the season.

Williams's coach Patrick Mouratoglou revealed the 31-year-old had "blocked" her back during practice before the third round but the American refused to lean on it as an excuse.

"I almost didn't play," she told reporters. "But, hey, I did, and at least I feel good that I tried the best that I could on this day."