Manny Pacquiao holds a grudge, which could be a good thing for his corner come Saturday night.

While Pacquiao was all smiles at a press conference Wednesday before his fight of the century against Floyd Mayweather Jr. at the MGM Grand Hotel and Casino in Las Vegas on Saturday. But his trainer, Freddie Roach talked about the boxer's inner drive.

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Uk.eurosport.yahoo.com reported that Pacquiao lived on the streets before he turned pro at age 14 to escape poverty.

Roach, however, revealed why Pacquiao was living on the streets at such a young age in the first place.

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"Manny ran away from home after his father ate his dog," Roach said, according to Yahoo.

The incident isn't as morbid as the statement makes it out to be, Larry Brown Sports reported.

"Pacquiao's father is not a monster," the website reported. "His family was simply so poor that his father had to make the difficult decision of cooking the family pet so they could eat. After leaving home, Pacquiao lived on the streets and did things like selling donuts for a nickel more than they cost at the store in order to survive. He became a professional boxer at age 14."

As Pacquiao prepares to fight Mayweather, boxingjunkie.com reported that Pacquiao harbors a similar resentment toward his opponent.

"The press conference is going to be boring," Roach said, according to boxingjunkie.com. "No one is going to say anything (interesting). I'm not; Manny has told me not to. But things are not how they look."

Roach said that Pacquiao became upset with Mayweather in 2010 when Mayweather posted a video online, referring to Pacquiao as "Pooch-iao." Mayweather also called Pacquiao "that little yellow chump" and said "I'll make that (expletive) make me a sushi roll and cook me some rice."

"Manny has never forgotten it," Roach said. "He won't say anything bad about anyone, but I can tell.

"He doesn't talk about things much, but he will store it up, and he has stored it up for five years. He hasn't forgotten, and it is ready to come out. He doesn't like this person because of their life and what they do. Manny is hungrier for it now. The last five years have really sunk in."