Maria Sharapova suffered a shock exit from Wimbledon on Monday as Germany's Sabine Lisicki avenged last year's semi-final defeat with a 6-4, 6-3 fourth round victory over the world number one.

Sharapova had romped to a straight sets win over Lisicki in last year's semi-final at the All England Club, but the top seed was completely out-played by the 15th seed this time.

The 25-year-old has been a finalist in three of the last four Grand Slams and arrived at Wimbledon on a high after winning the French Open for the first time earlier this month.

But she came back down to earth with a bump on Court One as Lisicki, beaten in the first round in her four pre-Wimbledon tournaments, produced one of the best performances of her career.

"I certainly had chances; I didn't take them. But I think a lot of the credit goes to my opponent," Sharapova.

"She played extremely well and did many things better than I did on this given day. She came after the rain delay really firing. You just have to hand it to her."

Sharapova could lose her world number one ranking depending on her rivals' results at Wimbledon, but she refused to be downbeat as she contemplated a well-earned rest.

"Of course you want to stay at the top as long as you can. Obviously everyone guns for that spot," she said.

"You can only use it as motivation but it will be nice to rest for a little bit and be in a home atmosphere. I've missed it for over two months."

Lisicki, who will play compatriot and eighth seed Angelique Kerber for a place in the last four, said: "It's just unbelievable. I'm so happy. I had lost the last three meetings with her, so it's nice to finally win one.

"I just went for my shots out there. I felt great, it's my favourite tournament. I love the crowd and playing on grass.

"I'm fighter and I fight to the last game. I think I'm getting better with each match."

The warning signs had been there for Sharapova, who won Wimbledon as a 17-year-old in 2004, as she hadn't been at her dominant best in the first week.

She had to survive a hard-fought clash with Tsvetana Pironkova before finally winning in three sets in the second round and it soon became clear Lisicki, pumped up to avenge last year's defeat, would pose her plenty of problems.

Lisicki has always thrived at Wimbledon, reaching the last four as a wild card last year and making a quarter-final appearance in 2009.

The big-hitting 22-year-old, dubbed 'Doris Becker' by German media for her powerful style, was quickly into her stride and broke for a 3-1 lead in the first set.

Even when nerves got the better of Lisicki as she served for the set, allowing Sharapova to break, it was the German's response that impressed as she came out all guns blazing and broke straight back to take the set at the second attempt.

A 45-minute delay did little to improve Sharapova's mindset and a double-fault presented Lisicki with two break points, which the German gratefully converted at the first attempt with a blistering forehand return.

When it came to serve for the match, Sharapova might have hoped for Lisicki to crack under pressure.

The German squandered one match point with a miscued forehand and couldn't take her second either, but a huge ace sealed victory and she fell to her knees in jubilation.