US’ Allyson Felix (R) competes in the wo

Allyson Felix cruises to victory in her semifinal heat of the women's 200 meters. (AFP PHOTO / JEWEL SAMAD)

Allyson Felix cruises to victory in her semifinal heat of the women’s 200 meters. (AFP PHOTO / JEWEL SAMAD)

US’ Allyson Felix (R) competes in the women’s 200m semi-finals at the athletics event during the London 2012 Olympic Games on August 7, 2012 in London. AFP PHOTO / JEWEL SAMADJEWEL SAMAD/AFP/GettyImages