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Video - Dementieva heads Russian tennis clean sweep
Elena Dementieva claimed gold in the women's tennis singles final after coming back from a set down to beat fellow Russian Dinara Safina.
Safina took the first set and looked to be on her way to her first Olympic title, but her compatriot rallied to win 3-6 7-5 6-3.
Dementieva's victory over her childhood friend completes Russia's podium sweep in the women's event.
Vera Zvonareva earlier dashed China's hopes, beating Li Na to claim bronze.
It is the first clean sweep in any tennis event since 1908, when Great Britain collected all three women's singles medals.
In an engaging and often gruelling final, Dementieva overcame a nervy, error-strewn first set to end Safina's 15-match winning streak.
Despite being hauled back from a break up early in the final set, the world number seven served out solidly to take the title and better her silver from Sydney in 2000.
"I never expected a medal - gold, silver or bronze," said Dementieva, 26, a runner-up at the French and US Opens in 2004.
"It's unbelievable. For me this is the best moment in my career. I'll never forget it. I've been dreaming about this moment since I was eight years old."
Safina - who had won all three of the pair's previous meetings this year - hugged the champion after she fell to her knees in celebration.
Zvonareva, a late call-up for the injured Maria Sharapova, clinched the bronze medal play-off against Li 6-0 7-5.
(L-R) Dinara Safina, Elena Dementieva and Vera Zvonareva with their medals
"Having three Russian girls left standing in the Olympics is a huge moment for Russia," Dementieva said.
"I know we were expecting and planning for some medals but I don't think anyone could expect three medals from the girls."
In the women's doubles, 2000 champions Serena and Venus Williams won their second career gold with a one-sided 6-2 6-0 victory over Spain's Anabel Medina Garrigues and Virginia Ruano Pascual.