With that being said, only the winner will have a real chance at title contention. At 147 pounds, that leaves WBA champion Paul Malignaggi, IBF champ Devon Alexander and WBC champ Floyd "Money" Mayweather, Jr. as possible opponents in the future.
Mayweather is the obvious choice, and probably the only real choice, for whichever established fighter comes away victorious.
This is going to be a battle. Anyone who watched any of the first three chapters of this rivalry should know that. There's not much difference between these two fighters, even if Pacquiao may have slightly more power.
I'm going with Marquez in this one, though. He should have won at last one of the previous matches against Pac-Man, and he will get over the hump here.
Marquez's main advantage is a good one: Pacquiao's aggression is a good thing most of the time, but it also can put him in tough spots. That doesn't always matter against lesser opponents, but Dinamita's counterpunching will make Pac-Man pay.
Pacquiao is used to dishing out punishment. His quickness, agility and stunning power is a lethal combination. Marquez, however, has the chin to withstand the punches and he's a tough, technically sound fighter with experience against Pacquiao's straight-forward approach.
At 39 years old, it's hard to say where Marquez will go after this fight. He's enjoyed an illustrious career, which began in 1995, and he doesn't have much more to accomplish. A win over Pacquiao would certainly vault him into title contention, whether he wants to accept it or not.
Marquez has the punching power and wherewithal to match Pacquiao's strengths, and he has the endurance to outlast Pac-Man.
In the end, redemption will be his.