The United States maintained their grip on the women's 4x400 meters crown on Saturday with their third consecutive world championships' victory.

The U.S. quartet of Sanya Richards-Ross, Allyson Felix, Jessica Beard and Francena McCorory crossed the line in three minutes 18.09 seconds, with Jamaica holding off Russia to take the silver medal.

Richards-Ross, who finished a disappointing seventh in the individual 400 final, staked the United States to a good lead on the first leg and they were subsequently never threatened.

It was very exciting. We had two youngsters in the team and they represented really well, said Richards-Ross. We all ran 49 seconds which has never been done before. It was a great team effort and I'm really happy to represent the United States.

The gold was also the first of the competition for Felix, who had been targeting an unprecedented world 200-400 double but had to settle for silver and bronze.

At this world championships I did not live up to my highest goals. But I am glad I still came back and got this medal, Felix said.

This was a team effort, it was so much fun. It is a blessing to be on the team. I will not celebrate tonight because I have the 4x100 tomorrow.

Russia had kept the pressure on Jamaica throughout but Shericka Williams said there had been no panic although Anastasiya Kapachinskaya had been pressing hard.

I felt the Russian girl on my shoulder. I didn't panic. I just carried on and she didn't surpass me, she added.

It is an incredible feeling. For the past four championships I have been to we have always got a medal in the relay. We wanted to keep that tradition.