Williams leads Dementieva head to head 7-2 and the bad news for Dementieva is both of Williams' losses ended in though third set tiebreakers with Williams committing her maximum errors.
Dementieva has improved her baseline game in recent months, but her serve remains a large liability especially against a player with a return of serve as good as Williams.
Should Venus win Thursday, she could then face her sister , the world number one Serena Williams. Serena, the Australian Open and US Open champion takes on 8th seeded Ana Ivanovic of Serbia, the French Open champion in the day's fourth quarterfinal.
Unexpectedly, Serena has met Ivanovic only once, at the 2006 US Open where she won in straight sets. Both Ivanovic and Williams play aggressive baseline games; however Williams withdrew from a tournament last week in Paris with a right knee injury and has not shown her best tennis yet this week in Dubai.
If Ivanovic performs at her highest level and Serena turns out to hit more errors than winners or is otherwise a step slow, an upset is possible, but an all Williams semifinal match is expected just in time for the weekend Dubai fans.
The Williams sisters are tied 9-9 head to head with Venus winning their last meeting 5-7, 6-1, 6-0 in November.