The Championships Wimbledon Sharapova stunned

Centre Court queen Maria Sharapova, the 2004 champion, was sensationally dumped out of Wimbledon on Wednesday losing 6-2, 3-6, 6-4 to Argentina's Gisela Dulko in the second round.

Dulko, who needed five knife-edge match points to seal victory after 2hr 13min, goes on to face Russian 10th seed Nadia Petrova for a place in the last 16.

But for Sharapova, defeat will cast further doubts over the ability of the sport's most bankable star to ever return to her former powers following a 10-month absence from the tour nursing a shoulder injury.

"It's the biggest win of my career because she's a great champion and on centre court in the most important tournament in the world," said the 24-year-old Dulko.

"It's a dream day. I played a poor second set but I kept fighting in the third. I was really nervous at the end. I didn't want it to go to 5-5 because she competes right to the very end."

Dulko was quickly a break ahead to lead 2-0 as the Argentine showed few nerves playing in front of 15,000 people.

The world number 45, had the Russian scampering from side to side and took the opening set in the eighth game courtesy of a sweeping, crosscourt forehand winner.

Sharapova was soon in trouble again as the slender Argentine nipped ahead to a 3-0 lead in the second set, courtesy of a break in the second game.

Dulko had lost both her previous meetings with Sharapova, but the Russian is nothing if not competitive and she was back in contention with a break to trail 2-3.

Two successive double faults from a suddenly frail-looking Dulko then allowed Sharapova to lead 4-3 which became 5-3 on a service hold.

The former champion then unleashed a succession of thunderous service returns to further dismantle the Argentine's crumbling confidence and she broke again to level the tie in the ninth game.

Sharapova, now with renewed potency, was ahead to lead 1-0 in the decider before Dulko ended the Russian's seven-game streak to level at 1-1.

Breaks were exchanged in the next two games with Sharapova fighting off two breaks points, as well as picking up a time violation, in the fifth game.

Dulko, who has reached the third round here on three occasions, refused to be overpowered and she broke to love to lead 4-3 as the Centre Court crowd warmed further to the underdog.

Sharapova saved four match points in a tense 10th game, but Dulko claimed an emotional victory when the Russian unleashed a wild forehand.