The United States powered unchallenged to Olympic gold in the women's 4x400 meters relay on Saturday.
The quartet of DeeDee Trotter, Allyson Felix, Francena McCorory and Sanya Richards-Ross crossed the line in three minutes, 16.87 seconds.
Russia's foursome of Tatyana Firova, Natalya Antyukh, Yulia Gushchina and Antonina Krivoshapka claimed silver almost four seconds back.
Jamaica took bronze as Novlene Williams-Mills, Shericka Williams, Rosemarie Whyte and Christine Day clocked 3:20.95.
"We thought it was going to be really tight," said America's Trotter.
"But I'm so proud of these girls, we're a great team."
Natalya Antyukh, who won gold in the 400 meters hurdles, said she had been nervous before the race.
"I knew I had to keep the second place and not to give it to Jamaica."
