Russia improved on their silver four years ago by taking gold
Russia claimed a surprise victory in the women's 4x100m relay as favourites Jamaica and Great Britain failed to get the baton round cleanly.
Jamaica, who swept the medals in the 100m final, failed to hand the baton on in the second changeover between Sherone Simpson and Kerron Stewart.
At the same time, there was a mix-up in the changeover between Britain's Montell Douglas and Emily Freeman.
With the field reduced, Belgium took silver with Nigeria claiming bronze.
Olympic 100m champion Shelly-Ann Fraser ran a smooth first leg and handed the baton on to Simpson, who put Jamaica in front going in the first bend.
But then the race unravelled for the overwhelming favourites as Simpson did not hand on to Stewart, meaning 200m Olympic champion Veronica Campbell-Brown did not get a chance to run the anchor leg.
"We had great success this year so we're not going to be ungrateful and complain," Campbell-Brown said.
Stewart added: "I'm not going to look at the race as a disappointment. We gave it our best shot - it didn't work out."
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Video - GB relay women distraught after mix-up
Watching from the sidelines, Jamaica's double Olympic sprint champion Usain Bolt jumped up and down in frustration.
He said after his victory in the men's 4x100m relay: "We were disappointed about the women, it was wonderful for us but disappointing for the women."
100m finalist Jeannette Kwakye and Douglas had also put Britain into a decent position before a tiring Douglas failed to get to Freeman's out-stretched hand in time.
"We messed up," Douglas said. "I was a little bit off-balance but when I went to put it in she was running away from me - it was too late.
"I just wanted her (Freeman) to stop but it just happened. It was just unlucky."
A tearful Freeman added: "I'm gutted. I don't think I went early but I don't know what happened. I'm just sorry."
Kwakye, who looked set to cap an impressive season with an Olympic relay medal, said: "It's devastating.
"We've practiced and worked so hard. It was a medal for us but hopefully we'll bounce back."
Russia, who settled for silver in 2004, stole top honours thanks to solid runs from Evgeniya Polyakova, Aleksandra Fedoriva, Yulia Gushchina and anchor Yuliya Chermoshanskaya.
The Russians moved into the lead coming off the final turn and Chemoshanskaya crossed the line in 42.31 seconds.
The US women's relay team did not qualify for the final after dropping the baton in Thursday's heats.