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