Floyd Mayweather's May victory over Manny Pacquaio has been thrown into doubt just days before the US boxing champion steps into the ring for what could be the final time.
Mayweather should be concentrating on upcoming opponent Andre Berto, but instead, after the Nevada State Athletic Commission (NSAC) this week called into question his pre-Pacquiao preparation, the American has been forced to speak out.
In response to the NSAC's claims that he bypassed protocol when using an intravenous drip on the eve of his fight against the Filipino, Floyd Mayweather put forward his defense via social media.
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Citing the US Anti-Doping Agency (USADA), who yesterday confirmed they gave Mayweather a "Therapeutic Use Exemption" to use the drip, the undefeated boxer maintained he is the one fighting against drug cheats in his sport.
The rebuttal came in the form of a series of Tweets:
However, despite Mayweather's conviction that he wasn't breaking any rules in the run up to his historic fight against Manny Pacquiao, NSAC insist only they can authorize such a procedure.
Speaking to BBC Sport, the organization's executive director, Bob Bennett, explained their tough stance:
"Anyone should know worldwide, if you fight in the state of Nevada we are the sole authority for approving a TUE."
"USADA has been known historically as the premier performance-enhancing drugs-testing organization and they have an outstanding record. But they do not have the authority to authorize a TUE to a fighter in the state of Nevada."
As you might expect considering his humbling defeat back in May, Manny Pacquiao has been quick to condemn his rival.
The Filipino has already demanded a rematch, arguing that Mayweather received favortism from USADA who had, Pacquiao says, denied him the right to use a specific pain-killer on his pre-existing shoulder injury.
The pair have had a long-running feud largely based around drug testing and this latest revelation will only intensify the dislike between the two camps.
Boxing fans: Do you trust Mayweather? And would Pacquiao even stand a chance in a rematch> Have your say in the comments below...