Boxer Manny Pacquiao made good on his threat and filed a defamation lawsuit against rival Floyd Mayweather Jr., as well as members of Mayweather’s family, his team and Golden Boy Promotions for allegations he says they’ve made that he uses or has used performance enhancing substances.

Despite the federal suit, filed Wednesday in U.S. District Court in Las Vegas, promoters on both sides of the heated dispute say it doesn’t necessarily kill the fight.

Pacquiao and Mayweather, widely considered the two best fighters in the world, are close to a deal to fight at the MGM Grand Garden Arena in Las Vegas on March 13 in what is expected to be the largest-grossing bout in history.

But the fight has come aground following a request by Mayweather that Pacquiao submit to Olympic-style drug testing that would be administered by the United States Anti-Doping Agency and which would include random blood and urine draws.

Pacquiao has agreed to submit to any testing requested by the Nevada Athletic Commission, which has regulatory jurisdiction over the fight, including random blood and urine draws. He has balked at agreeing to any outside agency.

His attorney, Daniel Petrocelli, said he felt the odds of a jury being empanelled and the case moving forward are “extremely high.”

“The statements the defendants made are absolutely false and nothing is more damaging to an athlete than to accuse him or her of cheating,” Petrocelli said in a telephone interview.

“Anyone who knows Manny is fully aware that he is one of the hardest-working athletes in the world, he prepares endlessly and his successes are the results of hard work and natural talent. As a result, he had no choice but to respond to these allegations legally.”

The suit names as defendants Mayweather; his father, Floyd Mayweather Sr.; his uncle and lead trainer, Roger Mayweather; Mayweather Promotions, his promotional company; Richard Schaefer, chief executive officer of Golden Boy Promotions and Oscar De La Hoya, president of Golden Boy Promotions.

The suit says “Golden Boy, Schaefer, de la Hoya, and the Mayweathers conspired to destroy Pacquiao’s reputation and call into question his victories over Golden Boy fighters, his career in general, and his legacy as one of the greatest fighters of all time.”

Schaefer declined Wednesday to react to the suit and said his attorneys would respond appropriately. Mayweather attorney John Hornewer said he advises the fighter in boxing-related matters only, would not be involved in defending the lawsuit and had no comment on it.

However, Schaefer did say that he remains hopeful that despite the suit and despite the vitriol between the sides that a deal can be salvaged and the fight still be held as planned. He said he has turned negotiations on Mayweather’s side over to Bruce Binkow, Golden Boy’s chief marketing officer. Top Rank president Todd duBoef is negotiating with Binkow on behalf of Pacquiao.

“I still hope that somehow a compromise can be found and that this fight can be saved,” Schaefer said. “I fully realize that this fight not happening is not only a big blow for the fight but it has much bigger, much more serious ramifications. I don’t even want to think about what’s next for Floyd, what this, what that.

“I want to exhaust any and all possibilities to get the fight done. Everything I have is going into finding a way to make this fight and getting a compromise that is acceptable to all parties.”

Arum said he is no longer considering Paulie Malignaggi as an alternative opponent for Pacquiao on March 13. He said he did research and discovered that few believe Malignaggi would have been a credible opponent.

Instead, Arum said if a Mayweather fight can’t be made, he’ll try to finalize a deal for a fight between Pacquiao and Yuri Foreman, who holds a super welterweight belt and who is promoted by Top Rank.

“Our preference if we go to Foreman would still be to fight March 13 at the MGM, but if there were another event on that night, we could go to March 20 at the Thomas & Mack (in Las Vegas),” Arum said.

But Arum said he’s still agreeable to a Mayweather-Pacquiao fight if Mayweather’s side will agree to all the testing be administered by the Nevada commission.

Pacquiao submitted a urine sample on Thursday morning Manila time, Arum said, at the request of the Nevada commission.

He said that if Keith Kizer, the executive director of the Nevada commission, ordered any subsequent tests, Pacquiao would submit to them.

“All they have to do is to agree that the testing and everything else in this fight is under the jurisdiction of the Nevada State Athletic Commission and we will have a deal,” Arum said. “Kizer is the regulator in charge of this fight and Manny would comply with any request he made, as he always has.”