World 100m champion Torri Edwards lost her appeal to be reinstated to the US Olympic team after the Court of Arbitration for Sport (CAS) maintained her two-year ban for drugs Tuesday.

The 27-year-old American tested positive for the prohibited stimulant nikethamide at an athletics meeting in Fort-de-France, Martinique on April 24.

Veteran two-time Olympic 100m champion Gail Devers replaces her in the 100 meters which begins on Friday.

The American authorities had imposed a two-year ban on Edwards after the sport's governing body -- the International Association of Athletics Federations (IAAF), had considered there were no exceptional circumstances exonerating the athlete in this case.