BURBANK, Calif. - Jose Aldo was born deep in Brazil's Amazon rain forest, while Frankie Edgar is from the Jersey Shore.
Both learned how to fight on the streets long before they ever stepped in a cage, and both UFC stars quickly picked up an important survival lesson.
"It's always better to fight somebody your own size," Aldo said with a grin.
As the first featherweight champion the UFC has ever recognized, Aldo occupies a unique niche in mixed martial arts history. Edgar is one fight away from earning a rare distinction of his own when they meet at UFC 156 on Saturday night in Las Vegas.
After several years of being an undersized lightweight who improbably rose to the top of his division with relentless conditioning and pure will, Edgar, a Toms River, N.J., native, is finally picking on guys closer to his own size.
With an upset win over Aldo, Edgar could add the 145-pound title to the 155-pound belt he once held, putting him alongside Randy Couture and B.J. Penn as the only fighters to win championships in two weight classes.
"I don't know if I'll be the biggest at 145 pounds, but I won't be as out-sized as I was at 155," Edgar said. "I'm definitely looking forward to it. This is something I've been thinking about for a while, and it's great to start right at the top with Jose."
The undercard of the UFC's annual Super Bowl-adjacent show features Rashad Evans' comeback fight against Antonio Rogerio Nogueira and heavyweight Alistair Overeem's return from a nine-month suspension for a failed drug test to meet Antonio "Bigfoot" Silva.
The main event matches two of the UFC's most prominent smaller fighters. Edgar (14-3-1) is an underdog yet again in his seventh consecutive UFC title fight, while the dominant Aldo (21-1) faces arguably his toughest test as a champion after fighting just once in 2012.
"He'll fight all five rounds the same way," Aldo said. "He doesn't give up. He's a champion of a higher division, and that's motivation for me. He has a great reputation. This was a fight I really wanted."
One day shy of exactly six years since his UFC debut, Edgar will take on another daunting challenge after narrowly losing his last two fights to lightweight champion Benson Henderson.
Aldo is in the UFC's top handful of pound-for-pound fighters, despite a 13-month absence from the cage caused by a series of injuries. His kicks are among the most vicious in MMA, and his overall agility in the cage can be stunning to opponents and fans alike.
But ever since Edgar broke an orbital bone in his face during his MMA debut in an unsanctioned bout in the Bronx, he has been willing to do just about anything to win a fight. He claims it's part of his upbringing - not in his loving childhood home, but in simply growing up in New Jersey.
"That's kind of the culture of the East Coast," he said with a laugh. "To fight on the boardwalk is part of what we do."
Edgar hasn't had to do any ridiculous weight-cutting, given that he normally walks around under 160 pounds, and he doesn't anticipate any problems making the 145-pound limit with all of his power intact. Edgar likely would be favored against any other featherweight fighter, but the good-natured former Rutgers University wrestler couldn't turn down an immediate title shot.
"If I win, it's going to take care of everything else," Edgar said. "The championship, the legacy, everything will be there. When I started out, I just wanted to make sure I was a person that could stick around and be a part of this sport, so to accomplish everything that I have is everything I ever imagined."
Aldo acknowledges it's more difficult for him to make 145 pounds for each fight, and he could be headed to lightweight in the near future. It's tough to argue, given his dominance at featherweight while rising from small-time promotions to the defunct WEC and the UFC, winning 14 straight bouts since November 2005.
In fact, Aldo has taken more damage from the Rio de Janeiro pavement than any opponent in the past year. While riding a motorcycle, Aldo was cut off by a car, leading to a crash in which he injured his right foot and leg.
The injury forced the postponement of this fight, originally scheduled for last October. Aldo got back to training after a few weeks off, determined to face the only serious threat to his featherweight supremacy.
"I was upset, because I really wanted that fight right then," said Aldo, who isn't eager to get back on a motorcycle. "I'm going to buy a car with my check from this fight. I've already got it picked out."