Latest results

The Frenchwoman looked nervous as she dropped the opening set but a 12-minute injury timeout changed the momentum.

Dementieva looked unhappy as she was forced to wait and the Russian never got her rhythm back, with Pierce claiming a 3-6 6-2 6-2 victory.

The Frenchwoman, seeded 12th, will play Kim Clijsters in Saturday's final after the Belgian beat Maria Sharapova.

Pierce started nervously against Dementieva, who was attempting to go one better than last year when she lost in the final.

A double fault on the opening point signalled a poor first set from Pierce, while the notoriously fragile Dementieva serve held firm.

If that is the only way she can beat me then it is up to her Elena Dementieva

The key moment came when Pierce called for the trainer at the end of the set and received treatment on her thigh and then her back.

Dementieva kept herself warm with some practice serves but was clearly not happy, and her rhythm never returned.

A rejuvenated Pierce stepped up her game and raced through the next two sets for the loss of just four games.

"You can change the game around by playing an unbelievable point or return but taking a 12-minute timeout, I don't think it was fair play," said Dementieva.

"But she can do it by the rules. If that is the only way she can beat me then it is up to her.

"I've never had such a long break before. I was trying to keep warm and stay focused. But I wasn't angry because that's the way she plays.

"She is trying to use any distraction she can but it didn't affect my game. It was all my fault."

Pierce responded: "I'm 30 years-old and I've been on the tour for 17 years. I would never do anything toward another player in that kind of way."

She added: "After I lost the first set I thought that I needed to get help because I just couldn't play that way.