Las Vegas - Floyd Mayweather Jr will challenge Puerto Rico's Miguel Cotto for the World Boxing Association (WBA) super welterweight title on May 5, less than a month before the American is due to report to jail.
Mayweather had requested that his three-month prison sentence for domestic battery be postponed until June so that he could compete in one more bout, an appeal that was granted by a Las Vegas judge earlier this month.
That bout was widely expected to be a long-awaited mega-showdown with Filipino Manny Pacquiao to decide the mythical title of of the world's best pound-for-pound fighter but the fighters' promoters could not agree on the date.
Instead, Mayweather will step up in class from his customary welterweight and take on three-division world champion Cotto at MGM Grand Garden Arena in Las Vegas.
"Miguel Cotto is a world-class fighter who can never be taken for granted and continues to prove he is one of the best in boxing," Mayweather, 34, said in a statement on Wednesday.
"It will be a challenge for me to compete with him at this weight, but this is the type of test I thrive on and gives me the motivation to train even harder.
"I have no doubt in my mind that my title belt collection will increase once again and Cotto's reign as champion will come to an end on May 5," added the American, a seven-time world champion in five weight classes.
Mayweather, a flamboyant boxer regarded as the best defensive fighter of his generation, improved his perfect professional record to 42-0 by claiming the WBC welterweight title from Victor Ortiz in September.
Cotto, 37-2 (30 KOs), successfully defended his WBA super welterweight crown with a 10th-round technical knockout win over Antonio Margarito in December.
"I am here to fight the biggest names in boxing," the Puerto Rican said of the May 5 bout in Las Vegas. "I've never ducked anyone or any challenge in front of me.
"I have accepted everything to give the fans what they like ... great and exciting fights. That is what the sport of boxing is all about."
The jail sentence Mayweather faces stems from a case in which he pleaded guilty in December to one charge of felony battery and no contest to two counts of harassment from a 2010 attack on his ex-girlfriend Josie Harris and verbal threats against two of his children with Harris.
Mayweather was sentenced to six months for that outburst, but the judge suspended half the jail term.