LAS VEGAS — The strain of dealing with the Haitian earthquake was too much for Andre Berto, forcing him to withdraw from his fight next week with Shane Mosley. The move could open up a much bigger fight matching Mosley against Floyd Mayweather Jr.

Promoter Richard Schaefer said Monday he was already working on trying to make a Mosley-Mayweather match, and said both boxers were interested in the bout.

"I'm going to do whatever I can to pull it off," Schaefer said. "I'm cautiously optimistic we can put something together. It would be a great fight, a long anticipated fight."

Mayweather has been looking for an opponent ever since his March 13 megafight with Manny Pacquiao collapsed amid Mayweather's demand for blood testing for performance enhancing drugs. Mosley would be an interesting choice, since he had links to the BALCO lab and says he unknowingly used steroids before his 2003 fight with Oscar De La Hoya.

Schaefer said he wasn't sure if Mayweather would demand blood testing for Mosley, but said he has already talked to the Mayweather camp and been given assurances he wants the fight. If negotiations prove successful, it would be held either May 1 or May 8 in Las Vegas.

"Mayweather is interested and so, of course, is Shane," Schaefer said. "Now it's a matter of negotiating the right deal structure that makes everyone happy."

Berto and Mosley were to meet a week from Saturday at the Mandalay Bay resort in a scheduled 12 round fight for Berto's WBC welterweight title. The fight against the veteran Mosley was to have been televised on HBO and would have been the biggest of Berto's career.

But Berto, who represented Haiti in the Athens Olympics, said he could not train properly for the fight in the wake of the devastating earthquake that hit the country where his parents were born.

"As a result of this disaster, I am mentally and physically exhausted and therefore I have no choice but to withdraw from my bout," Berto said in a statement.

Berto, who has many relatives on the island, had been in training in Florida and was scheduled to arrive in Las Vegas on Wednesday. But he said he could not go forward, despite the fight being "an opportunity I have dreamt of since childhood."

"I lost several family members to the earthquake and after two days without word, was relieved to learn that my sister, Naomi, and her daughter, Jessica, survived, but were left homeless," Berto said. "I have seen the pain in my parents' eyes as they attempt to understand what has happened to our homeland and recognize a place they once called home."

Berto (25-0, 19 KOs) was born in Miami but fought for Haiti in the 2004 Olympics after narrowly missing the U.S. team. He has been involved in charity and relief efforts in his parents' homeland for several years.

Berto said he appreciated the support he's gotten since the earthquake struck and hoped that the people of Haiti would be kept in everyone's thoughts and prayers as work begins to rebuild the country.

"The rebuilding of Haiti is not something that will happen overnight, but I am fully dedicated to helping the Haitian people recover from this catastrophic event," he said.