Reigning world 100m champion Christian Coleman is facing a two-year suspension after revealing on Tuesday he missed a drugs test last December.
The US sprint star -- who only narrowly avoided being banned last year after three violations of anti-doping "whereabouts" rules across 2018 and 2019 -- revealed details of his latest missed test in a statement on Twitter.
Coleman said he had unsuccessfully challenged an Athletics Integrity Unit finding that he missed a test on December 9, 2019.
"And now this might result in me being suspended from other filing failures that occurred well over a year ago at this point," Coleman said.
Coleman's impassioned statement on Twitter was accompanied by what appeared to be a copy of his formal notification from the AIU of a missed test.
If the missed case is confirmed, Coleman could face a suspension of up to two years, ruling him out of next year's Olympic Games in Tokyo.
Coleman, 24, escaped suspension on a technicality ahead of last September's World Championships in Doha after it emerged he had committed three whereabouts failures in a 12-month period.
Those offences were recorded on June 6, 2018, January 16, 2019 and April 26, 2019.
However Coleman had successfully argued that the first missed case should have been backdated to the first day of the quarter -- April 1, 2018 -- meaning the three failures fell just outside the required 12-month period.
But news that Coleman missed another meeting with testers in December means that his offences in January and April of last year now come into play.
Under World Anti-Doping Agency rules, any combination of three whereabouts failures -- either missing a test or failing to file paperwork on time -- within a 12-month period is deemed a doping offence punishable by a two-year suspension.
Although two-year suspensions can often be reduced to one year if there are mitigating circumstances, Coleman's recent history means he is likely to be facing an uphill battle if he appeals.
In his Twitter post on Tuesday, Coleman said the missed test in December had been a deliberate attempt by anti-doping officials to try and catch him out.
"I think the attempt on December 9th was a purposeful attempt to get me to miss a test," Coleman said in a statement.
"Don't tell me I "missed" a test if you sneak up on my door (parked outside the gate and walked through...there's no record of anyone coming to my place) without my knowledge," Coleman said.
Coleman said testers had visited when he was out shopping for Christmas presents at a nearby mall, something he said could be verified by his bank statements and receipts.
"I was more than ready and available for testing and if I had received a phone call I could've taken the drug test and carried on with my night," he said in his statement.
"I was only made aware of this attempted drug test the next day on December 10th, 2019 by the AIU when I got this failed attempt report out of nowhere. I was completely unaware anybody tried to test me the day before."
The report from the doping control officer posted by Coleman said the tester had arrived at his apartment and had failed to get a response after "multiple, loud knocks were made every 10 minutes" for an hour-long period.
A doorbell next to Coleman's door was pressed but no ring could be heard. No attempt to reach Coleman by phone was made, according to the document.
"I've been contacted by phone literally every other time I've been tested," Coleman said. "Literally. (I don't know) why this time was different. He even said he couldn't hear the doorbell so why wouldn't you call me?"
Coleman said testers had reappeared two days later to carry out a test which he was present for.
"And I've been tested multiple times since, even during quarantine," Coleman added.
"But of course, that doesn't matter, and the fact that I have never taken drugs doesn't matter either."