Defeat for Williams sisters
No all-Williams final in Beijing
Last Updated: 14/08/08 4:59pm
Dementieva: Silver in Sydney
Venus and Serena Williams are out of the Olympic tournament after suffering quarter-final defeats on Thursday.
Serena was the first to go, beaten in three sets by Elena Dementieva.
The American world number four took the opening set but Dementieva, the silver medallist in Sydney eight years ago, recovered to win 3-6 6-4 6-3.
Russia's Dementieva is renowned for being affected by nerves at key moments and she squandered two match points at 5-2 before wrapping up her win in the next game.
"It was a very exciting moment," Dementieva told reporters. "This is the biggest tournament for me this year."
Dementieva now faces an all-Russian semi-final with Vera Zvonareva, who beat Austria's Sybille Bammer 6-3 3-6 6-3.
Venus followed younger sister Serena out of the Beijing event after a 7-5 7-5 loss to home favourite Li Na.
The double Olympic champion missed out on a third title after Li recovered from a sluggish start in front of a noisy Centre Court crowd.
Venus looked back on track after recovering from 3-0 down to lead 4-3 in the second set, but the Wimbledon champion slumped again and Li claimed the win on her second match point.