LAS VEGAS – Manny Pacquiao wants to put an end to any doubts regarding his superiority over Juan Marquez and claims he is aiming for a knock out when the two meet for a fourth time in December.Three bouts in eight years have not resolved the rivalry so they meet again on December 8 at the MGM Grand Garden in Las Vegas.‘I want to erase the doubt of the last three fights,’ Pacquiao said. ‘There’s so many people still asking if I won the fights. I think to myself, "Something is wrong. I have to do it again.”‘This time, I will train hard to put this fight up in the history of boxing. I want to make this fight short. I want to knock him out.’ Although they are extending a rivalry to rare lengths in modern boxing, the fighters and promoters believe fans will warm to the matchup when they remember just how good the first three fights were.Pacquiao and Marquez fought to a draw in 2004, while Pacquiao won by split decision in 2008 and again by majority decision last year. The bouts featured knockdowns, wild momentum swings and fascinating contrasts in technique - but Marquez and many fans still believe he won all three fights, while Pacquiao says he clearly won the last two.With a combination of unfinished business and unmatched financial reward, Pacquiao and Marquez both had plenty of incentive to get together again. They have fought at 125, 130 and 144 pounds, and their fourth fight will be a straight welterweight contest at 147.Pacquiao (54-4-2, 38 KOs) is coming off his first loss since 2005, a wildly disputed decision to Timothy Bradley. Still stinging from that embarrassment, he says he is going back to the ferocious, relentless style of fighting that made him an eight-division champion.Marquez (54-6-1, 39 KOs) has tested Pacquiao more than any opponent, with counterpunching skills and comprehensive boxing knowledge that can negate many of Pacquiao’s strengths. While Pacquiao has a plan to recapture his best form, Marquez believes the only way to be sure he’ll finally get his hand raised is to stop the Filipino congressman. Marquez swore off the rivalry and nearly retired in frustration immediately after Pacquiao’s victory last fall, but agreed to return after a few months to cool down.‘I won all of the last three fights,’ Marquez said. ‘I would like the referee to raise my hand. Everybody knows I won the fights, and I don’t know what happened with the judges. I have to take it out of the judges’ hands this time.’