Mayweather, who is unbeaten in 42 professional fights hit the scale at 151 pounds while Cotto, who lost twice in his professional career, registered 154 in the weigh in for Saturday night's major boxing event.
The Mayweather vs. Cotto fight includes a power packed line up of main supporting bouts featuring the popular Mexican idol Canelo Alvarez who will face veteran Shane Mosley. The 21-year old Alvarez in unbeaten in 39 fights while Mosley, who recently lost to pound for pound king Manny Pacquiao has a record of 46-7-1(39 KOs).
Jessie Vargas vs. Steve Forbes and Deandre Latimore and Carlos Quintana are also included in the main card
while 10 other aspiring boxers make up the supporting event.
Mayweather is favored to win based on early predictions by boxing experts. But Cotto (7-1 underdog), who is fresh from an impressive performance over former foe Antonio Margarito in their recent rematch, is confident he will win the fight.
Cotto, who is expected to attack Mayweather in the body to pave the way for a clearer shot to the head said he is ready for everything.
"I can’t just go to the body," Cotto said
of his specialty. "I’m here to fight. If he wants to run, I’m ready for that. If he wants to face me, I’m ready for that. I’m ready for everything."
Cotto was chosen by Mayweather as his opponent for his May 5 fight after a series of failed negotiations with Filipino boxing superstar Manny Pacquiao.
Mayweather earlier talked to Pacquiao over the phone with a $50 million guaranteed purse but with a single share in the pay-per-view (PPV) revenues. Pacquiao, who is amenable to a 50-50 purse sharing, rejected Mayweather's offer and said it was an "embarrassing" offer.
Pacquiao is facing unbeaten Palm Spring boxing star Timothy Bradley
on June 9, also at the MGM Grand Garden Arena.
If both Mayweather and Pacquiao emerge as winners in their upcoming fights, boxing fans say they could still face each other in the ring before the end of the year.
Pacquiao has recently announced his retirement from boxing after two more fights to pursue his career in politics.