Chelsea have confirmed Mudryk's sample carried an "adverse finding" this morning.
And the Ukraine international took to social media to also state: "I can confirm that I have been notified that a sample I provided to The FA contained a banned substance.
"This has come as a complete shock as I have never knowingly used any banned substances or broken any rules, and am working closely with my team to investigate how this could have happened.
"I know that I have not done anything wrong and remain hopeful that I will be back on the pitch soon. I cannot say any more now due to the confidentiality of the process, but I will as soon as I can."
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