The much-anticipated showdown between Manny Pacquiao and Floyd Mayweather, tentatively scheduled for March 13 at the MGM Grand in Las Vegas, has collapsed, Top Rank promoter Bob Arum told on Wednesday night.

“The fight’s off,” Arum, who promotes Pacquiao, said from Las Vegas.

The fight died after a last-ditch attempt at mediation between Top Rank and Golden Boy, which represents Mayweather, failed in an effort to determine the drug-testing protocol.

Pacquiao had agreed to move off his hard-line stance of refusing a blood test inside 30 days before the fight, but Mayweather wouldn’t budge off his desire for random testing all the way until the fight, Arum said. Nor would Mayweather agree to a public apology for remarks he made accusing Pacquiao of using performance-enhancing drugs, Arum said.

“I am very disappointed that we could not make this fight for the fans and I am angered because of the false accusations from Golden Boy and the Mayweather camp that I used some type of drugs, and that is why I have instructed our American lawyers to proceed with the lawsuit to clear my name,” Pacquiao said in a statement.

The fight was to have been on HBO PPV, a sure blockbuster many believed would break the all-time pay-per-view record of 2.44 million buys set by Mayweather’s 2007 fight with Oscar De La Hoya, who owns Golden Boy Promotions. But Arum said he had informed HBO PPV boss Mark Taffet that the fight was off.

Had the fight done the monster numbers organizers expected, it would have likely generated in the neighborhood of $200 million with the fighters receiving in roughly $40 million apiece.

Arum said Pacquiao agreed to shorten the window for a blood test to 24 days before the fight. In order to receive a Nevada boxing license, Pacquiao took the standard annual blood test 24 days before his May 2009 fight with Ricky Hatton.

“Manny accepted what was on the table and Mayweather rejected it,” Arum said. “Haymon and Schaefer tried to convince Floyd all [Tuesday night] and [Wednesday] and he wouldn’t agree to it. He didn’t want the fight. He never wanted the fight. I always knew the fight wouldn’t happen.” -ESPN