In a boxing world where very few fights capture the imagination of the man in the street, Saturday's WBO welterweight showdown in Las Vegas between holder Manny Pacquiao and Juan Manuel Marquez is sure to get pulses racing.

Both boxers thrive on aggression and their eagerly anticipated third meeting after two closely contested bouts is expected to provide a conclusive chapter to a trilogy of high quality and electrifying action.

Southpaw Pacquiao, a 7-1 favorite, will be bidding for a 15th consecutive victory since his loss to Erik Morales in March 2005 and his trainer, Freddie Roach, has predicted a knockout by the Filipino inside six rounds.

Mexican Marquez, meanwhile, is fueled by thoughts of vindication after repeatedly claiming he won their first two encounters.

The boxers fought to a draw in May 2004 before Marquez lost his WBC super-featherweight title to Pacquiao in a controversial split decision in March 2008.

Now it's time to shed doubt over who the best fighter is, Marquez said while preparing for the scheduled 12-round bout at the MGM Grand Garden Arena. I want to win this fight because I believe I won the first two.

We are not the only ones saying that we won those first two fights. A lot of people out there, a lot of fans and a lot of the media, agree.

Marquez gave Pacquiao added motivation by wearing a T-shirt bearing the legend: We Were Robbed when their November 12 showdown was first promoted in the Philippines.

While Pacquiao claims he was insulted by that fashion statement, Marquez believes he has just as much incentive for their third and final meeting.

It is personal for me too, said the 38-year-old Mexican, who has a career record of 53-5-1 with 39 knockouts said. If he is upset about me saying that I won the first two fights, I am upset that I haven't got the decisions.

Pacquiao, who has never indulged in the trash-talking so common in boxing and has often been criticized for being too much of a gentleman in the ring, says he has never been as fired up for a bout.


I almost can't wait for this fight, the 32-year-old told Reuters. I have never been so motivated as I am for Saturday.

I want to prove that he (Marquez) was wrong in wearing that T-shirt claiming he won the last two fights.

So this is kind of a special fight, the most important fight in my boxing career, because I want this fight to be the answer to all the doubts that have been raised.

Pacquiao, who has won world titles in an unprecedented eight weight divisions, believes he is a much improved fighter since he last met Marquez in the ring.

I'm more experienced, especially in my strategy and techniques. I'm more improved in (throwing) my right hand, my movement side to side, and my timing, said the Filipino, who has a career record of 53-3-2 with 38 knockouts.

His trainer Roach, a shrewd tactician who has been uncannily accurate with his fight predictions, forecast a Pacquiao victory inside the distance at the MGM Grand.

I don't think the fight's going to last six rounds, Roach told Reuters. It's going to be a helluva fight until it ends because one thing about Marquez is that he will fight.

Marquez has put on a little bit of muscle and he is a little bigger upstairs. It looks like he might want to exchange with us and I hope that happens.

The bespectacled Roach has long believed that Marquez, a three-division world champion, has been the toughest opponent Pacquiao has faced in his illustrious career.

The Mexican recovered from three knockdowns in the opening round to earn a draw when they first clashed in May 2004 and he is renowned for his aggressive strategy and fearless counter-punching.

There's no question Marquez has the most difficult style for us, said Roach. But Manny is a completely different animal to the guy that fought Marquez the first time. I don't think Marquez is going to be able to get up from this Manny Pacquiao punch.