Junior welterweight slugger Lucas Matthysse, citing a viral infection that has kept him from training, has withdrawn from his Sept. 17 fight against Erik Morales, Golden Boy promoter Richard Schaefer told ESPN.com Thursday.
Argentina's Matthysse was supposed to fight former three-division champion Morales of Mexico in one of the featured bouts on the Floyd Mayweather Jr.-Victor Ortiz HBO PPV undercard at the MGM Grand in Las Vegas.
Schaefer said Morales would remain on the card and that his matchmakers are seeking a new opponent.
Schaefer said he had no doubt that Matthysse's illness was real, not a ploy to get out of the fight.
"They did send us a certificate from a doctor but this is a situation where I don't even need to see a certificate," Schaefer said. "The guy was favored to go and win a world title against a legend like Erik Morales on the biggest pay-per-view card of the year. Who the hell would want to pull out of that?"
Schaefer said he found out about Matthysse's situation late Wednesday.
"He has a very severe virus, which totally dehydrated him and weakened him," Schaefer said. "I was told he had to be admitted to the hospital to deal with the dehydration issues, but he is going to be OK."
When Matthysse (28-2, 26 KOs) dropped out Schaefer said Morales' first request was that Golden Boy try to line up a rematch with titleholder Marcos Maidana, who won majority decision against him in an April barnburner.
Maidana (30-2, 27 KOs), who is also promoted by Golden Boy, had been scheduled to fight Robert Guerrero in San Jose, Calif., on Aug. 27.
But Guerrero dropped out less than two weeks before the fight because of a severe shoulder injury. Not wanting to let his 12-week training camp go to waste, Maidana's team arranged a hometown defense for him in Argentina on Sept. 23, but he could have scrapped it to face Morales (51-7, 35 KOs), Schaefer said.
"Erik came to us and said he was looking forward to the fight with Matthysse and that he will fight anyone in his place," Schaefer said. "He said, 'Get me Maidana.' So we reached out to Maidana, but he prefers to fight in Argentina at this point."
Schaefer said there are three potential opponents for Morales, although he declined to name them.
"We should have something to announce in the next 24 hours," he said.
One possibility, however, is Anthony Crolla (20-2, 9 KOs) of England. He was originally supposed to fight Morales before Golden Boy suddenly dropped him in favor of Argentina's Jorge Barrios, who later dropped out because of visa issues and was replaced by Matthysse.
Crolla, who would be taking a huge step up in competition, is still scheduled to fight on the untelevised undercard and could easily move up the card.
Although Matthysse has lost two of his last three bouts -- both on HBO -- but he is one of the more crowd-pleasing fighters in the division and both defeats came on questionable split decisions to former titleholders in their hometowns: Zab Judah and Devon Alexander.
Schaefer said whomever replaces Matthysse, he is still looking forward to seeing Morales fight.
"Erik Morales is always in exciting fights," Schaefer said. "You could never see Erik Morales in a bad fight, so I am excited no matter who he fights."
Dan Rafael covers boxing for ESPN.com. Follow him on Twitter.