BURBANK, Calif. - Junior Dos Santos got into only a few street fights as a kid in Brazil, and he doesn't remember winning any of them.

"I was a crying boy," the 6-foot-4, 240-pound Dos Santos said over lunch this week. "I got beat up. I didn't like it."

Dos Santos thinks he could have been content as a busboy or a laborer. He didn't have the rampaging fire of many mixed martial artists, no desire to prove the whole world wrong with his fists.

How he became the UFC's heavyweight champion still surprises Dos Santos, a relative latecomer to MMA who has grown into one of the sport's best strikers, its most talented boxer -- and one of the sport's most pleasant people.

"You have to keep going, and you can never give up," Dos Santos said. "It's not just a saying. It's true. You have to train and work, and those things you do become automatic. It's not easy, but I love it."

Dos Santos (14-1) will defend his title for the first time at UFC 146 in Las Vegas on Saturday night, meeting two-time champion Frank Mir (16-5) in the main event of a pay-per-view card stacked with heavyweight talent -- including Cain Velasquez, who lost the UFC belt to Dos Santos last fall.

Although he's headlining a pay-per-view for just the second time, Dos Santos already won his title in stunning fashion on the biggest stage possible. When he stopped Velasquez just 64 seconds into the first round in Anaheim, Calif., with a vicious overhand right, he also introduced MMA to a national television audience on Fox in what UFC President Dana White called the biggest fight in the promotion's history.

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Dos Santos immediately became a celebrity on two continents, putting the quiet kid from Salvador, Brazil, into a spotlight he never imagined. Years of training with the famed Nogueira brothers didn't prepare him for the attention and wealth resulting from his remarkable rise.

"I come from a small city, and people recognize me a lot on the streets now," Dos Santos said. "I'm making proud my family and my mom. I never imagined anything like this in my life. Everything I do, I try to do my best. I'm just enjoying what I deserve. When you work hard, you deserve to get nice things."

Before Dos Santos stumbled upon jiujitsu while working out at a regular gym, he worked 12-hour shifts as a busboy six days a week, making little money, but getting fed by sympathetic cooks. Although he was already strong from other work as a laborer, pouring concrete and cutting wood slabs in a factory, he had little athletic skill and no MMA training until a jiujitsu coach, Yuri Carlton, saw his potential.

Dos Santos also had a hunger for a better life, even if he didn't advertise it. Although he was happy in menial jobs, he was ambitious.

"Suffering makes you a better person," Mir said. "Adversity makes all people greater. I didn't have a hard life. Cigano, it made him tough. He already had a certain toughness level before he got into an octagon."

Although it's tough to believe when looking at his enormous shaved head, Dos Santos used to show up for practice with his hair in a ponytail, earning him the nickname "Cigano" -- a Portuguese word for gypsy. He learned various additional skills and moved into MMA, training over the next 16 months before his first pro fight, when he knocked out his first opponent with some sort of soccer kick to the head.

"When I beat him, it was like someone had pulled a whole airplane of weight off my shoulders," Dos Santos said.

Dos Santos got a boxing coach, Luiz Carlos Dorea, but his game really took off six years ago when he began sparring with Antonio Rodrigo Nogueira and Antonio Rogerio Nogueira, Brazil's famed Pride Fighting stars. Dos Santos took a daily beating from the world's best, and he learned something from every bruise and black eye.

"I trained every day, and it didn't matter if you got beat up or no," Dos Santos said. "I came to Rio the first day, and I got beat up. I was thinking about going back home. That was too much. But the next day, I was ready to get hit again. ... Today, they don't want to spar with me."

Dos Santos rose through the heavyweight ranks, joining the UFC in October 2008 with a knockout of fellow Brazilian Fabricio Werdum. He has beaten an impressive list of heavyweights, including Cro Cop Filipovic, Gabriel Gonzaga, Roy Nelson and Shane Carwin, culminating in his title win over Velasquez.

Dos Santos takes none of his success for granted. He had knee surgery after winning the belt last fall, but returned to training with a determination to stay on top against Mir, a savvy veteran with the most wins in UFC heavyweight history.

"I know it's a tough fight, but I like a tough fight," Dos Santos said. "I'm OK to fight anybody. I like this challenge."