Christian Coleman, the reigning world champion in the 100-meter dash, was suspended Wednesday by the Athletics Integrity Unit for missing drug tests.

The AIU updated its list of athletes on provisional suspension to include Coleman, hours after the American sprinter revealed details of the case. He is temporarily banned from competition until a final decision at a hearing conducted under the World Athletics Anti-Doping Rules or the Integrity Code of Conduct.

Coleman said earlier on Twitter that drug testers were unable to find him Dec. 9 while he was at a nearby mall Christmas shopping. That was his third infraction in a 12-month period.

Athletes are required to list their whereabouts for an hour each day when they must be available to be tested. A violation means an athlete either did not fill out forms telling authorities where they could be found, or that they weren't where they said they would be when testers arrived.

Coleman is a favorite for Olympic gold in the 100-meter dash heading into the Tokyo Games that have been postponed to next summer due to the coronavirus pandemic.

He said in his post he's been appealing the latest missed test for six months with the AIU, which runs the anti-doping program for World Athletics. He explained there was no record of anyone coming to his home and that if he had been called he was only five minutes away.

It's the second time Coleman has faced a potential ban for a whereabouts violation.

Coleman won the 100 meters at the world championships in Doha, Qatar, last September after the U.S. Anti-Doping Agency dropped his case for missed tests because of a technicality.

"I have never and will never use performance enhancing supplements or drugs," Coleman wrote Tuesday. "I am willing to take a drug test EVERY single day for the rest of my career for all I care to prove my innocence."