Second seed Venus Williams was stunned by Bulgarian Tsvetana Pironkova on Tuesday, failing to reach the women's singles semifinals at the Wimbledon Championsihps.

The four-time Wimbledon winner was defeated 2-6, 3-6.

"I had a lot of opportunities and a lot of short balls. I just seemed to hit each one out," said the world number two.

Pironkova, who had never reached the third round at a Grand Slam, said she didn't expected such an achievement at the All England Club.

"Coming here, I really just wanted to play a good game, to maybe win two rounds. But semifinal looked to me very far," said the world number 82.

In the semifinals, Pironkova will meet Russian 21th seed Vera Zvonareva, who saw off former world number one Kim Clijsters 4-6, 6-4 and 6-2.