Contrasting fates for Williams sisters

Venus Williams crushed Maria Sharapova 6-2 6-2, while her younger sister Serena was upset by Samantha Stosur in the quarter-finals of the Stanford Classic.

Seven-time Grand Slam champion Venus had not beaten Sharapova in three previous matches on hard courts, but she was the more aggressive and accurate in the hard-hitting rallies while destroying the Russian's second serves.

Sharapova only hit 11 winners and committed 30 forced errors.

"She's a tremendous athlete and was probably 10 steps faster to the ball than I was," said Sharapova, who was playing her fifth tournament since returning from shoulder surgery.

"I should have taken the opportunities I had. That's something that comes along with playing and right now, it's not on autopilot for me."

Venus will now face third seed Elena Dementieva of Russia who advanced with a 6-2 6-4 victory over Slovakia's Daniela Hantuchova .

The chance of an all-Williams final, however, had been ended when Australia's Stosur employed a huge serve, hard forehand and deft slice to upset Wimbledon champion Serena (pictured) 6-2 3-6 6-2.

Stosur had held four match points against Williams in Sydney earlier this year, but was unable to convert them in a three set defeat, but on Friday, was the much more consistent player.

"I knew I had my chances in Sydney and I wanted to get in the same position, and this time I got over the line," Stosur said.

After fighting off two break points at 2-2 in the third set, Stosur then broke the second-ranked Williams to love.

The Australian then won the next three games in routine fashion and took the contest when Williams double faulted.

"I didn't want a repeat of Sydney so once I got the lead I knew I had to step up and take the pressure to her, which is may be one of the reasons why she double faulted," Stosur said."

Stosur will play France's Marion Bartoli, who fought off two match points against fourth seed Jelena Jankovic in a 3-6 7-6 6-3 victory.