Relay drama leaves US women facing time trial

The United States' women's 4x100m relay team face a nerve-jangling time trial to force their way into Friday's final after a dropped baton drama Thursday. US star Allyson Felix was bumped by a Brazilian rival as she prepared to hand over to English Gardner, knocking her off balance and sending the baton tumbling to the floor. Brazil, who had initially finished fourth, were disqualified.