Jankovic struggled to cope with Safina's big-hitting game
World number one Jelena Jankovic had her bid for Olympic gold ended in the quarter-finals by Russia's Dinara Safina, who triumphed 6-2 5-7 6-3.
The Serbian, who was playing in her first tournament since rising to the top of the rankings, fought hard before being overpowered in the deciding set.
Safina goes through to face China's Li Na in the women's singles semi-finals.
In the doubles, Venus and Serena Williams beat Elena Vesnina and Vera Zvonareva to reach the last four.
Despite her defeat Jankovic was pleased with her run to the quarter-finals as she has been struggling with a calf injury.
"You cannot expect miracles to happen when you have some problem. I've been taking injections before I went on court just to be able to perform, otherwise I couldn't play," she said.
Her conqueror Safina was overjoyed to have reached the last four.
"I'm too excited to think about it," said the 22-year-old Russian.
The Williams sisters had both crashed out of the singles on Thursday but the second seeds, who had earlier cruised past Ayumi Morita and Ai Sugiyama in straight sets, kept their hopes of a medal alive with a 6-4 6-0 win over their Russian opponents.
Ukrainian sisters Alona Bondarenko and Kateryna Bondarenko also made progress, reaching the semi-finals with a 6-1 3-6 7-5 win over Italians Flavia Pennetta and Francesca Schiavone.
And Spaniards Anabel Medina Garrigues and Virginia Ruano Pascual, seeded four, went through 5-7 7-6 (8-6) 8-6 at the expense of the United States' pair of Lindsay Davenport and Liezel Huber.
Safina's run of success came to an end in the early hours in Beijing when she lost in the doubles after a stunning fightback from the Chinese pair of Yan Zi and Zheng Jie.
Safina was the top seed with Russian compatriot Svetlana Kuznetsova but despite leading 5-2 in the deciding set they lost 6-3 5-7 10-8 to the fired-up Chionese pair, who were roared to victory by the passionate home fans.
The second singles semi-final, which will take place on Saturday, will an all-Russian affair between Vera Zvonareva and Elena Dementieva.