(CNN) -- WBO welterweight champion Miguel Cotto will take a one-pound advantage over Filipino Manny Pacquiao into Saturday night's superfight in Las Vegas.
Puerto Rico's Cotto weighed in at 145 pounds in front a 5,000 strong crowd at the MGM Grand Arena, with Pacquiao tipping the scales at 144 pounds.
Pacquiao is bidding for a world title at a fifth different weight and was backed by vociferous supporters ahead of the eagerly-anticipated bout.
He looked relaxed and smiled as he stripped to his boxer shorts, while Cotto looked more intense.
There was a brief, angry exchange between Pacquiao's trainer Freddie Roach and the Cotto camp after the champion got off the scales but order was quickly restored and both fighters addressed the crowd in their native languages.
Pacquiao, who is rated the best pound-for-pound fighter in the world by many boxing experts, has previously won recognized belts at fly, super-bantam, super-feather and lightweight during his remarkable career.
It is his first fight since a stunning knockout of Britain's Ricky Hatton sixth months ago at the same venue.
Pacquiao, who's won 49 fights, lost 3 and drawn 2, is being lined up for a money spinning fight with American Floyd Mayweather, but first must get past the determined Cotto, who has held a world title every year since 2004.
Pacquiao is rated as favorite by Las Vegas oddsmakers, but Cotto has just one defeat in 35 fights with 27 knockouts.