America overpowered the Russian challenge to win the women's 4x400 metres relay at the World Championships.
Sanya Richards, who is just 18-years-old, ran a devastating anchor leg to come home in three minutes 22.63 seconds.
Russia, who had set the early pace, were pushed into the silver medal position while defending champions, Jamaica picked up the bronze.
World 200m silver medallist Anastasiya Kapachinskaya slowed down on the third leg to allow the chasing Jearl Miles Clark of America to catch her.
Lorraine Fenton, who had won silver in the individual 400m, raced hard on the last lap to get Jamaica back in to contention but no-one could catch the fast-finishing Richards.
The British quartet of Lee McConnell, Jenny Meadows, Catherine Murphy and 400m hurdler Natasha Danvers battled hard but struggled to cope in a class field.
Danvers found herself in fourth position at the start of the final lap but she faded badly and crossed the line in seventh place.
1. United States (Me'Lisa Barber; Demetria Washington; Jearl Miles Clark; Sanya Richards) 3:22.63.
2. Russia (Olesya Zykina; Yuliya Pechonkina; Anastasiya Kapachinskaya; Natalya Nazarova) 3:22.91.
3. Jamaica (Sandie Richards; Allison Beckford; Ronetta Smith; Lorraine Fenton) 3:22.92.
4. Germany (Claudia Marx; Birgit Rockmeier; Claudia Hoffman; Grit Breuer) 3:26.25.
5. Poland (Monika Bejnar; Malgorzata Pskit; Anna Jesien; Grazyna Prokopek) 3:26.64.
6. Britain (Lee McConnell; Jennifer Meadows; Catherine Murphy; Natasha Danvers) 3:26.67.
7. Cameroon (Mireille Nguimgo; Carole Kaboud Mebam; Delphine Bertille Atangana; Hortense Bewouda) 3:27.08.
DQ Senegal (Fatou Bintou Fall; Mame Tacko Diouf; Aminata Diouf; Amy Mbacke Thiam).