Wimbledon's 2004 champion Maria Sharapova tumbled out of the tournament in the opening round for the first time, beaten at her own game by fellow-Russian Vitalia Diatchenko 6-7(3) 7-6(3) 6-4 as the evening shadows crept across Court Two on Tuesday.

Sharapova, seeded 24th, managed to stay with qualifier Diatchenko, who plays with a similar heavy-groundstroke style, through long baseline rallies and numerous deuce games, hoping her experience would tell.

"I definitely had several chances in the match. Although not playing my best tennis, I opened up a few doors and was a couple points away from winning this match. But sometimes you put yourself in a better or winning position and you don't finish through," a subdued Sharapova told reporters.

She said she would take time to study how she lost.

"I don't shy away from mistakes and errors, looking back at film, learning from what went wrong. It's not always pleasant moments, but sometimes those are the ones you need to get better."

Diatchenko, 27, had a medical time-out at 3-3 in the first set for treatment on her side and back. She appeared to be moving well afterwards but called the trainer again in the final set.

Nerves jangled as the first set reached its climax and she could not find the shots to disturb the 31-year-old five-times Grand Slam winner in the tiebreak, which Sharapova won with an unreturnable serve.

Sharapova, 31, broke Diatchenko's serve early in the second set and looked to be cruising until her opponent roared back with stunning stokes to win three games in a row and bring the scores level.

The younger woman, world number 132, was more composed during the second tiebreak, earning early minibreaks and winning the set with a big serve that Sharapova put wide.

"The transition from clay to grass has been tougher for me as I've gotten older," Sharapova said. "That's just a matter of training, getting through the soreness in the first week or so."

Both players roared with effort as they exchanged shots and each pulled off some stunning winners in the third set.

Sharapova broke twice but each time Diatchenko replied in kind and she wrapped up an unlikely victory in just over three hours when the former champion double-faulted.

"She swung away. She played extremely aggressive. I was playing a little bit too defensively for what I should have been doing. She was there to win it and she did," Sharapova said.

(Reporting by Clare Lovell, editing by Ed Osmond) ((clare.lovell@thomsonreuters.com;))