The International Testing Agency says it has provisionally suspended Kenyan sprinter Mark Odhiambo after he tested positive for an anabolic steroid.
Odhiambo has been removed from the men's 100-meter heats scheduled later Saturday.
The agency says he is challenging the suspension with the Court of Arbitration for Sport. He tested positive in a sample given Wednesday in Tokyo for methasterone, according to the agency.
The positive test was reported Saturday by the Olympic testing laboratory in Tokyo hours before Odhiambo was due to compete.
The 28-year-old ran a career-best time of 10.05 seconds six weeks ago, according to his biography on the World Athletics website.