DUBAI (AFP) - Alize Cornet of France scored a career-best victory and created a major upset in the process with victory over world number one Serena Williams in the Dubai Open, which ended hopes of an all-Williams final.

Cornet, making her way back into the world's top 20 after a long interval, won their semi-final 6-4, 6-4.

Earlier, Venus Williams reached only her second final in 16 months and with a 6-3, 6-2 win over Caroline Wozniacki, in which she dominated the former world number one from Denmark from start to finish with her heavier, and sometimes cleverly angled, driving.

But Cornet dashed hopes of the first all-Williams sisters final in more than four years as she played an almost impeccable match, full of solid serving and sturdy rallying.

She changed the mood of the match when she took advantage of Serena'a errors to break serve to 5-4 in the first set.

Cornet closed out the set without fuss, the pressure was suddenly on WIlliams, whose first tournament this was since injuring her back in last month's Australian Open.

Cornet rode the momentum to break again, and although Serena pulled that back, she was increasingly tense, dropping serve again to go 3-4 down in strange circumstances.

First she put an uncharacteristic and inappropriate drop shot into the net and then she failed to run a ball down, wrongly thinking her serve had been out.

Cornet could not convert the four match points she had at 5-3, but got all her first serves in at 5-4 and pressed Serena into the errors which ended the match.

"It's my best ever win but I haven't realised it yet," Cornet said. "I played a very good match. I didn't even realise who I was playing and that's the way I had to be.

"I forgot it was Serena on the other side, and just got on with my game."