Allyson Felix of the U.S. takes the baton from team mate DeeDee Trotter in the women's 4x400m relay final...
Allyson Felix (L) of the U.S. takes the baton from team mate DeeDee Trotter in the women's 4x400m relay final at the London 2012 Olympic Games at the Olympic Stadium August 11, 2012. REUTERS/Dylan Martinez (BRITAIN - Tags: OLYMPICS SPORT ATHLETICS)