World 100 metres champion Christian Coleman could be banned from the Tokyo 2020 Olympics after revealing he missed a drugs test in December.
The American, who escaped a ban after three missed tests across 2018 and 2019, posted an image of his unsuccessful test report on Twitter.
He is now facing a two-year ban for three missed tests within 12 months, which would rule him out of the re-arranged Olympic Games next year.
It has been confirmed that he has been charged and provisionally suspended by the Athletics Integrity Unit (AIU).
Coleman, the fastest man in the world for the past three years, escaped punishment last year after missing tests on June 6, 2018 and January 16 and April 26 of 2019.
Missing three tests in 12 months is the equivalent of a doping failure, but the sprinter successfully argued that the 2018 case, a filing error, should be pushed back to the first day of the quarter, April 1, and subsequently out of the year-long window.
However, if the December failure is confirmed the January and April cases will come back into play and mean that three tests have been missed in 12 months.
Coleman, who after avoiding a ban last year went on to win gold in the 100m and 4x100m relay at the 2019 World Championships in Doha, acted defiantly when he was cleared last time.
In a statement on the latest revelation, he once again took aim at the United States Anti-Doping Agency (USADA) and the AIU.
"A few days ago, the AIU came to a decision that I've been appealing for six months that I missed a test on December 9, 2019," he said.
"And now this might result in me being suspended from other filing failures that occurred well over a year ago at this point.
"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.
"Knocked while I was Christmas shopping five mins away at the mall (I have receipts and bank statements) and didn't even bother to call me or attempt to reach me.
— Christian Coleman (@__coleman) June 16, 2020
"I was more than ready and available for testing and if I had received a phone call I could have taken the test and carried on with my night.
"The AIU has to stop playing man.
"Two days later they came back to test me and followed the normal protocol and called and of course there were no issues with my test.
"I think the attempt on December 9 was a purposeful attempt to get me to miss a test."
Athletes in all sports must register their whereabouts at certain times so they can be drug-tested at random.
Coleman is the current favourite for the Olympic title at Tokyo 2020, which was pushed back due to the COVID-19 crisis.
"I have never and will never use performance enhancing supplements or drugs," Coleman added.
"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.
"I support USADA, WADA (World Anti-Doping Agency) and the AIU to keep athletes and competition clean and fair.
"But the system must change.
"I thought the point of the organisation was to keep the sport clean by testing everyone and catching cheaters.
"Not attempt to catch people when they're not home and make no attempt to actually test them and mess with the livelihoods of people who are clearly not doping.
"The sport is in trouble and needs some sort of reform."
The AIU told insidethegames they would not comment on an ongoing case but they did note their procedures for out-of-competition testing, which are in conflict with Coleman's claim that he should have received a phone call.