Shane Mosley has signed his contract to face Floyd Mayweather Jr. in a welterweight megafight on May 1 at the MGM Grand Garden in Las Vegas, Mosley attorney Judd Burstein said late Friday.

Mayweather, whose March 13 fight with Manny Pacquiao fell apart because of a disagreement over drug testing protocol, is expected to sign on to the deal in the next few days with a formal announcement expected next week.

The fighters, who each spent the last decade ranked somewhere among the top in the lists of the best pound-for-pound boxers in the world, have won world titles in eight different weight classes.

While details of the deal were not revealed, Mayweather has the option for an immediate rematch in the event he loses to Mosley.