Russia's Anastasia Myskina celebrated her biggest career victory as she beat defending champion Kim Clijsters to reach the final of the Sparkassen Cup.

Clijsters was going for a third straight Leipzig title but saw her hopes ended in a third-set tie-break.

The Belgian third seed was 4-1 up in the final set but Myskina came back to win the two-hour match 6-4 5-7 7-6.

Myskina will now face world number one Serena Williams, who crushed Justine Henin 6-4 6-2 in the other semi-final.

"I played great tennis," said Myskina, whose victory made sure she will enter the world top 10 next week.

"I'm not too worried about my ranking. The most important thing for me is to keep playing the way I did today.

"The ranking will take care of itself if I can do that."

The Russian kept ripping forehands down the line as the two players battled it out from the baseline.

But Clijsters helped her opponent by double faulting away the game when she led 6-5 in the final set and again in the tie-break when she had a 3-1 lead.

Myskina had also charged back from 2-5 and two set points down in the second set before Clijsters fended off a break chance at 5-5 and saved the set.

Williams lost to Henin in the German Open final in May but she was in a class of her own this time.

The French Open, Wimbledon and US Open champion needed just 70 minutes to overpower the Belgian third seed.

"I'm feeling great. I'm not tired at all," said Wiilliams, who is aiming for her eighth title of the year.

"I hope I don't stay at this level. I'm not on the level I'd like to be. I don't come to the net as much as I like, I'm not hitting the ball as well as I'd like."

Sparkassen Cup semi-final results