Jarrell Miller will miss out on a $5million (£3.8m) pay day if his fight with Anthony Joshua is cancelled.
The American heavyweight failed a drug test last month and now faces a wait to see if he will be banned.
Any suspension will see him miss out on a shot at Joshua's three heavyweight world titles - and a career-high pay day.
Miller would also bank a percentage of the pay-per-view sales if does fight Joshua in New York on June 1.
And according to ESPN, he would then earn a futher $3m for his subsequent two fights, if he lost to the Brit.
Were he to upset the odds and inflict a first defeat on Joshua, Miller would rake in another eight figures from the rematch.
Jarrell Miller responds to failed drugs test ahead of Anthony Joshua fight
The self-styled 'Big Baby' has denied the allegations but must wait to learn his fate.
The adverse finding is reported to be for GW1516, a metabolic modulator also known as cardarine and endurobol.
Miller is likely to face a hearing before the New York State Athletic Commission to decide whether he will be allowed to fight at Madison Square Garden.
Eddie Hearn, Joshua's promoter, tweeted on Tuesday morning that VADA had informed him of its results.
Hearn tweeted: "We have been informed by VADA that there has been an adverse finding in Jarrell Miller's sample collected on March 20th, 2019.
"We are working with all relevant parties and will update with more details soon. AJ's preparation continues for June 1st at MSG."
Hearn could now need to find a replacement fighter for what would be Joshua's USA debut.
Joshua retained his WBA, IBF, WBO and IBO titles when he stopped Alexander Povetkin in September.
Miller's camp, Salita Promotions, also acknowledged the adverse finding on their Twitter account.
A statement read: "We are in the process of obtaining further information about VADA's finding and will have more to say soon on this developing situation.
"In the meantime Jarrell continues to train for his June 1 fight against Anthony Joshua."
The 30-year-old was kickboxing in 2014 when he tested positive for methylhexaneamine in a urine sample and was suspended for nine months by the California State Athletic Commission.
