LAS VEGAS: The goat really got David Diaz.

The WBC lightweight champion made it from the Olympics to the pinnacle of prizefighting with a firm belief that his fate was in his own hands. He absorbed that philosophy from his parents while they raised nine kids, including baby David, as Mexican immigrants in Chicago.

After earning an unlikely berth on the 1996 US Olympic team with that same tenacity, Diaz determined his own fate when he quit boxing for two years-and again when he returned to the sport in 2002. Four years later, Diaz rallied from a heavy deficit for a knockout victory that eventually secured his title belt. Diaz’s life is stuffed with examples of why superstitions should be powerless over him. So why did Diaz want to sprint off the Santa Monica Pier on Monday at the sight of a goat in a Chicago Cubs hat? Well, because Diaz is also a lifelong Cubs fan who knows just enough about the Curse of the Billy Goat, the 63-year-old kerfuffle that’s supposedly keeping his long-suffering club from winning it all, to be very afraid.

The promoters of his upcoming fight with Manny Pacquiao jokingly recruited the goat to provide color at the news conference, yet Diaz wasn’t really laughing.

“Man, that billy goat scared me, dude,” Diaz said with a laugh. “Can you imagine if the Cubs start messing up, and that gets around? I’m not having that on my ticket.”

Diaz wants nothing more than an honest chance to do the improbable. Pacquiao is a heavy favorite in the Vegas sportsbooks for the Filipino superstar’s first fight at 135 pounds, and Diaz is widely expected to struggle against Pacquiao’s formidable power.

But it’s never been a good idea to count out Diaz-not since the raw Golden Gloves champion beat favored prospect Zab Judah twice to take the 139-pound spot on the US team in the Atlanta Games. He then posted a stunning comeback win in 2006, falling behind on all three judges’ scorecards before knocking out Jose Armando Santa Cruz-a victory that led to his coronation. “He’s had a tremendous career when he’s been behind,” said promoter Bob Arum, who re-signed Diaz after the fighter’s two-year break. “No matter how hopeless it looks, he stays in there and never quits.” Diaz clearly isn’t the star in Saturday’s fight. Wearing a ThunderCats T-shirt and shorts that made him look like any young Las Vegas vacationer, Diaz spent several moments at Wednesday’s news conference patiently waiting as Pacquiao signed gloves and posed for pictures before the fighters could do their own photo shoot.

Yet Diaz doesn’t mind, since he obviously appreciates everything he’s earned. He got choked up when he thanked his father, who overcame minimal education and tight financial circumstances to raise nine children in Chicago.

“He’s my first best friend,” Diaz said. “He’s the man I look up to. Doesn’t read, doesn’t write, and he still took care of nine kids. ... He loves boxing like I do. I asked him one time if I could go out and play football, and he said, ‘That’s a sport for animals.”’ Diaz also is a mid-major sports celebrity in Chicago these days, throwing out the first pitch at a Cubs game and even making an improbable wrist shot to win a silly promotion at a Blackhawks game.

He duly impressed Hawks coach Denis Savard, who’s expected to accompany Diaz into the ring Saturday night. Yet even on the verge of an $800,000-plus payday for taking on Pacquiao, Diaz still drives around Chicagoland in a 1991 Honda with no air conditioning- or at least he did, until he loaned it to his nephew. “My wife’s got a car, and she lets me use it once in a while,” Diaz said. “We’ve got to get a new one. Probably have to move up to a ‘98.”

Diaz won’t acknowledge thinking much about how his life would change if he knocked off Pacquiao. Jim Strickland, Diaz’s longtime trainer and beloved adviser, has said he might finally retire if Diaz wins, though Diaz claims he wouldn’t allow it. And though he claims to have more superstitions than he could mention, Diaz knows the responsibility for knocking off Pacquiao rests solely on his unimposing shoulders-goat or no goat. “I have to go out there and perform,” Diaz said.

“If I don’t do it, I’m not going to win. I never thought I’d get the championship, but now that I have it, I don’t want to let it go.”