Randolph Ross, a U.S. Olympic 400m sprinter, and Lawrence Cherono, a Kenyan marathon star, were provisionally suspended in anti-doping cases and excluded from the world track and field championships.
Ross, eliminated in the Tokyo Olympic 400m heats, was banned for tampering with the doping control process, according to the Athletics Integrity Unit, which handles doping cases in track and field.
The alleged violation arose out of an investigation into a potential whereabouts violation after an unsuccessful attempt to drug test Ross on June 18.
Ross, third in the USA Track and Field Outdoor Championships 400m last month, will not race the world championships 400m that starts Sunday.
Cherono, a Boston and Chicago Marathon champion, tested positive for the banned substance trimetazidine, a form of heart medication, from a May 23 sample. Cherono, fourth at the Tokyo Olympics, will not race the world championships marathon on Sunday.
Provisional suspensions can be issued while awaiting a hearing on charges to determine an official punishment, if any.
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