Melbourne - Fifth seed Ana Ivanovic crashed out of the Australian Open at the first hurdle Monday, stunned by unheralded world number 142 Lucie Hradecka, a qualifier from the Czech Republic.
The Serb blew a strong lead to lose 1-6, 6-3, 6-2 in front of her stunned supporters at Rod Laver Arena.
It was the first major upset of this year's tournament and threatens to derail Ivanovic's plans to rebuild a career that has stalled since she won the French Open in 2008.
The 27-year-old looked on course for an easy victory as she raced away with the first set in just 21 minutes, breaking Hradecka three times in the process.
But she went down 3-0 in the second after conceding an early break, managing to get back to 3-4 before Hradecka broke her again to force a deciding set.
Hradecka, who won a silver medal in doubles at the London Olympics and has three Grand Slam doubles titles, refused to be intimidated by an opponent ranked 137 places above her.
She went up a break in the third game of the final set then maintained the pressure to snatch another break in the seventh and make it 5-2.
Hradecka fired down an ace to bring up two match points at the death, screaming with delight as Ivanovic blasted the second into the net.
"I was so nervous in the beginning and at the end, my hands were shaking," she said.
It is not the first time Hradecka has proved an irritant to Ivanovic, with the Czech taking her to three sets in the opening round of Wimbledon in 2009, only to let victory slip away when she squandered two match points.
"I'm so happy that I did it this time," she said.