American heavyweight Jarrel Miller is to appeal against a decision to deny him a fight licence against Anthony Joshua.
The New York State Athletic Commission refused him a licence to fight on 1 June after he returned an "adverse finding" in a drug-testing sample.
Miller returned the adverse finding on 20 March and his team have now requested his B sample be tested.
But the decision by NYSAC - who sanction the bout - has currently left Joshua without an opponent for his US debut at Madison Square Garden.
Miller, 30, said: "The facts will prevail and I shall be vindicated.
"My team and I stand for integrity, decency and honesty and we will fight this with everything we have."
"I am absolutely devastated upon hearing the news my boxing license has been revoked in NY State and I will be vigorously appealing this decision.
"I have never knowingly taken any banned substance and when I found out the news last night I was totally shocked.
"This was a voluntarily test that I was very happy to do and these results came just one week after another voluntarily test that I had taken which was completely clean.
"I refuse to just lie down and let my dream be taken away from me when I know in my heart that I've done nothing wrong.
"I don't have anything to hide and the truth will make itself known."