Much to prove for Marquez vs. Pacquiao

Juan Manuel Marquez looks at Manny Pacquiao and wonders what might have been.
Marquez has given the Pac-Man, regarded by many as the top pound-for-pound fighter in the world, two of his toughest fights, a draw and a split-decision win for the Filipino congressman. Deep down, Marquez believes he won both fights, and believes the course of history would have been altered if he had gotten both decisions.
Still considered a top-five pound-for-pound fighter, it could be Marquez who sits atop the sport as his opponent does. Rather than live in the past, though, Saturday night (HBO PPV, 9 p.m. ET) the 38-year-old Marquez has that third chance at Pacquiao he's been waiting for.
"That's why we are doing this third fight. The first two were very close and this fight should end all doubt," Marquez said. "We are not the only ones saying we won the fights. There are a lot of fans and media out there saying the same thing — that we won those two fights."
There is something else Marquez (53-5-1, 39 KOs) must prove in order to win the fight: that his move upward in weight class will not hurt him. The first two fights were at lightweight, this one will be at welterweight, a class Pacquiao (53-3-2, 38 KOs) moved up to and has been rampaging through since he defeated Oscar De La Hoya in 2008.
Marquez has only had one fight at welterweight, a 12-round unanimous-decision loss to Floyd Mayweather. In that fight, the added weight seemed to take away some of his trademark quickness. This time around, Marquez trained differently and believes that will make all the difference.
"I think it is a question of getting stronger and keeping the speed," Marquez said. "That is key to victory — being as strong and as quick as he is."
Always drawn to a good exchange, Marquez is happy to be squaring off against one of his chief rivals, and the man with whom he's had two classic bouts with.
"I would rather fight Pacquiao three or four more times than fight Mayweather once," Marquez said. "Mayweather is a defensive fighter — he doesn't let you fight, but we know Pacquiao comes to fight and he is a spectacular fighter. He is always going to give you a fight, and that's why I know it will be a war between us."
As the world waits for a possible Mayweather-Pacquiao showdown, which many have theorized could materialize after this fight, the dangerous Marquez could throw a wrench into the whole equation by defeating Manny on Saturday night. An attainable goal in his eyes, because Team Marquez believes they've already done so twice.