Allyson Felix became the most decorated performer in World Athletics Championships history as she helped the United States to victory in the mixed-gender 4x400m relay.
Felix was level with Usain Bolt on 11 gold medals at the event prior to Saturday's race in Doha.
But the 33-year-old, who became a mother in November, helped set up Michael Cherry to power clear on the last leg.
Poland - which decided to send its two men out first in an attempt to build up an unassailable lead - held the advantage until Cherry came into play, with Felix having run second.
Cherry simply had too much for the rest of the field, with Javon Francis claiming silver for Jamaica and Bahrain coming in third.