By Rob Woollard
Floyd Mayweather has hit back at accusations he violated anti-doping rules by receiving a saline and vitamin injection on the eve of his fight with Manny Pacquiao.
A report on the SB Nation sports news website said Mayweather had broken World Anti-Doping Agency (WADA) regulations by having an IV infusion in Las Vegas on May 1.
The United States Anti-Doping Agency (USADA) leapt to Mayweather's defence, saying the injection was legal and reports to the contrary were "false".
"I follow and have always followed the rules of Nevada and USADA, the gold standard of drug testing," Mayweather said in a statement.
"I am very proud to be a clean athlete and will continue to champion the cause."
Mayweather is chasing history in Las Vegas on Saturday (Sunday NZT) when he meets Andre Berto in a bid to match Rocky Marciano's 49-0 record.
USADA earlier said reports on the controversy had contained a "multitude of errors" and were "riddled with significant inaccuracies and misrepresentations".
"We believe it is important to immediately correct the false suggestion Floyd Mayweather violated the rules by receiving an IV infusion of saline and vitamins," said the powerful anti-doping watchdog which led the fall of disgraced cyclist Lance Armstrong.
USADA said Mayweather applied for and was granted a Therapeutic Use Exemption for the IV infusion, in accordance with regulations set by the Nevada State Athletic Commission (NSAC).
"Mr Mayweather's use of the IV was not prohibited under the NSAC rules at that time and would not be a violation of the NSAC rules today," the statement said.
It said Mayweather, a voluntary participant in the USADA program, had formally applied for the TUE after the infusion.
The agency said although the application was not approved until after the fight, Mayweather "did disclose the infusion to USADA in advance of the IV being administered".
"Furthermore, once the TUE was granted, the NSAC and Mr Pacquiao were immediately notified even though the practice is not prohibited under NSAC rules," it added.
The SB Nation report said Mayweather's infusion had come to light after USADA agents visited the boxer at his Las Vegas home the day before the Pacquiao fight, to conduct a random unannounced test.
The report said the IV consisted of two separate mixes of saline and vitamins which had been administered to address dehydration concerns.
It added that while the substances in question were not prohibited under WADA rules, administering them intravenously was a breach of WADA regulations.
WADA guidelines say IV infusions are prohibited because they can be used to mask the use of performance enhancing drugs, increase plasma volume levels and distort the values of an athlete's biological passport.
However, a USADA source later told news agency AFP because Mayweather obtained a TUE, no offence had been committed under WADA rules.
AFP