Dominican Republic's Felix Sanchez (R) jumps over a hurdle ahead of Trinidad and Tobago's Jehue Gordon, Kerron Clement of the U.S. and Britain's David Greene (2nd R-L) during their men's 400m hurdles semi-final at the London 2012 Olympic Games at the Olympic Stadium August 4, 2012. REUTERS/Pawel Kopczynski (BRITAIN - Tags: OLYMPICS SPORT ATHLETICS)