Jelena Dokic saw her hopes of defending the Princess Cup title dashed as she was beaten 7-5 2-6 3-6 by Kim Clijsters.

Clijsters achieved revenge for her semi-final defeat by Dokic in Tokyo last year to set up a meeting with Serena Williams in Sunday's final.

World number one Williams was not on top form against fellow American Amy Frazier but emerged a 7-6 6-3 winner.

Clijsters dropped her serve twice in the first set to go 1-4 down before pulling off two breaks of her own to level at 5-5.

But the Belgian third seed dropped her serve again in the following game and Dokic closed out the set.

Clijsters received a code violation at 1-1 in the second set after hitting the ball into spectators' seats but it proved to be a turning point.

She broke Dokic twice in the fourth and eighth games to level the match and went 3-0 up in the final set.

Her 10th double fault in the fifth game allowed Dokic to level at 3-3 but the defending champion surrendered her serve at 3-4 and Clijsters calmly served out for the match.

"The code violation actually helped me. I got all my anger out there and once I started keeping the ball in more, she started making mistakes," said Clijsters.

"I don't know what I was doing in the first set. My serve just wasn't there today. I will obviously have to play at a higher level against Serena."

Williams was taken to a tie-break by Frazier in an error-strewn first set but powered through to take it 7-0.

She continued to struggle with her accuracy in the second set but simply had too much power for Frazier, who contributed to her own downfall with 10 double faults.

"Obviously I made a lot of errors. I didn't serve or return as well as I normally would but it's good to have a tough match like this to get me on my toes for the final," said Williams.

"What makes a champion is to be able to win when you're not playing well. If I do what I know I can do I think it will be a positive result tomorrow."

Princess Cup semi-final results

Kim Clijsters (Bel, 3) bt Jelena Dokic (Yug, 2) 5-7 6-2 6-3
Serena Williams (USA, 1) bt Amy Frazier (USA) 7-6 6-3