A capacity crowd of 5,500 at the MGM Grand Garden Arena in Las Vegas watched the two rivals step onto the scale and jump the last hurdle prior to Dec. 8's fourth and final showdown.
Pacquiao, 34, weighed in at 147 pounds and Marquez, 39, weighed in four pounds less, at 143 pounds.
Marquez’s lean and muscular physique has drawn concerns from Freddie Roach, Pacquaio’s trainer.
"I asked Manny to do a drug test for this fight because I believe that Marquez is a much bigger person now—and I'm not sure exactly how he is getting there,'' Roach said, according to Jon Saraceno of USA TODAY Sports.
Roach later retracted those comments on Dec. 7, claiming he was “just joking,” according to Saraceno.
Weight has been a continual issue of dispute for Pacquiao when inking fights.
Before his last bout, Pac-Man tried to get Miguel Cotto to come down to the 147-pound welterweight limit, but the fighter balked and accepted an offer from Floyd Mayweather to fight him instead at a higher limit.
Eventually, Timothy Bradley moved up to Pacquiao's desired weight group and beat the champion by a split decision.
Dinamita and Pac-Man have both been through it all in their careers, as well as against one another. In each of their three previous head-to-head fights, they have fought at different weight limits. Although, their previous bout was fought at the same limit.
Before the pair’s most recent bout on Nov. 11, 2011, Pac-Man weighed in at just 143 pounds, while Marquez came in at 142.
Even though this will be the fourth and final installment of this series, this fight will not definitely result in defining who the better fighter is. That is, unless one of them decisively finishes the fight or knocks out the other.
Any type of doubt or uncertainty as a result of another controversial decision would send Marquez home from Vegas disappointed for a fourth time.
He looks in prime shape, though, and as ready as he will ever be in his final shot at taking down Pacquaio once and for all.
Full Pacquiao vs. Marquez main card weigh in results
Manny Pacquiao 147 vs. Juan Manuel Marquez 143
Michael Farenas 130 vs. Yuriorkis Gamboa 130
Miguel Vazquez 135 vs Mercito Gesta 134
Patrick Hyland 126 vs. Javier Fortuna 126