Melbourne - Third seed Maria Sharapova was knocked out of the Australian Open by Slovak Dominika Cibulkova on Monday, the second major upset in as many days.
The Russian, who took a medical timeout between the second and third sets, crashed 3-6, 6-4, 6-1 against the 20th seed in the fourth round to follow Serena Williams out of the tournament.
Cibulkova had never been beyond the fourth round in six previous attempts in Melbourne, although she has made the last eight at all the other three Grand Slams.
Her shock win set up a quarter-final encounter with either eighth-seeded Serb Jelena Jankovic or Romanian Simona Halep, seeded 11.
"I was 100 percent sure I could win. I never doubted myself even when I lost the first set," she said. "I knew what I needed to do. The most important thing is to believe in yourself."
It was an error-strewn and see-sawing match in which Cibulkova won five straight games in the second set and then lost the next four.
After racing through the first set Sharapova, who has reached eight major finals and won four, with her last success coming at the French Open in 2012, appeared to have a problem with her left buttock.
The Russian, who is on the comeback trail from a shoulder injury, had endured two tough matches before meeting the Slovak and admitted after beating Alize Cornet on Saturday that she must improve.
She got off to the best possible start on Rod Laver Arena, making the most of an early Cibulkova double-fault to get the break.
Sharapova held with a powerful forehand down the line and while she put pressure on Cibulkova's next service game, the Slovak held firm to stay in touch.
A wild forehand from the third seed gave Cibulkova two break points in the next game, but she failed to take her chance to pull level.
It went with serve until the world number three again made the most of some feeble serving from Cibulkova to drill a forehand winner cross-court to go 5-2 in front.
But her killer instinct deserted her at the crucial moment and she failed to serve out for the set. However, the Slovak suffered the same nerves, hitting a double-fault on set point to go a set behind.
Some of the serving was woeful and the Russian's first double-fault of the match gave Cibulkova an early break in the second and she held to take a 2-0 lead.
All of a sudden, Sharapova's form deserted her and a wide forehand handed her opponent a 3-0 lead.
The Russian could hardly win a point and went she 5-0 down. Stunned, Sharapova woke up and pulled a break back and then held to make it 5-2.
But her hard work was in vain as Cibulkova finally served out for the set.
Sharapova took a medical timeout at the changeover and was broken immediately on her return, with her movement appearing hindered.
The Slovak held and the pressure was on Sharapova, who came through a crucial third game after saving two break points to stay in touch.
But she was broken again in the fifth and there was no way back with a backhand wide handing Cibulkova a well-deserved win.
The result blows another big hole in the women's draw after top seed Williams went out against Ana Ivanovic on Sunday.
Results from the Australian Open on Monday (x denotes seeding):
Grigor Dimitrov (BUL x22) bt Roberto Bautista Agut (ESP) 6-3, 3-6, 6-2, 6-4
Dominika Cibulkova (SVK x20) bt Maria Sharapova (RUS x3) 3-6, 6-4, 6-1
Simona Halep (ROM x11) bt Jelena Jankovic (SRB x8) 6-4, 2-6, 6-0
Victoria Azarenka (BLR x2) bt Sloane Stephens (USA x13) 6-3, 6-2