LOS ANGELES (AP) - When Josesito Lopez and Saul "Canelo" Alvarez stood toe-to-toe and stared each other down Tuesday on historic Olvera Street, the supposedly undersized Lopez was the one looking down at his opponent.
Maybe their Sept. 15 bout isn't such a gross size mismatch after all. Maybe Lopez really has another shot at an incredible upset.
The matchup is the latest unlikely chapter for Lopez (30-4, 18 KOs), a virtually unknown fighter outside of his native Southern California before last month. With just four weeks to prepare as a late replacement opponent, his stunning upset victory over welterweight star Victor Ortiz catapulted him to fame.
After three prospective Canelo opponents were unable to fight, Lopez capitalized by accepting an invitation to jump up yet another weight class to take on Alvarez, the beloved young 154-pound champion and one of boxing's most impressive punchers.
Lopez already had one Rocky moment this year, yet he believes he's got a few sequels in him.
"I'm definitely the underdog again, but I give it my all in the ring," Lopez said. "I fight my heart out. I like to think I can take a pretty good punch."
Lopez and Alvarez formally announced their fight at a downtown Los Angeles park in front of several hundred eager fans. While Alvarez and Lopez are only worried about facing each other, their promoters realize they're also in for a fight in Las Vegas in two months.
In a boxing rarity, this Golden Boy-backed card at the MGM Grand Garden will be held just down Tropicana Avenue from a major card for Top Rank, headlined by Julio Cesar Chavez Jr.'s much-anticipated middleweight bout with Argentine star Sergio Martinez at the Thomas and Mack Center.
Neither Golden Boy CEO Richard Schaefer nor Top Rank's Bob Arum blinked and moved his card off Mexican Independence Day weekend, one of the highest-profile slots on the boxing calendar. The Top Rank show is a pay-per-view event, while Golden Boy's card is free to Showtime subscribers.
"We're going to do what we need to do from a business perspective," Schaefer said. "We're not going to be influenced by what Bob Arum does. ... If you have a choice and you can afford to do a non-pay-per-view, it's probably in the fighters' best interests to do it."
Alvarez (40-0-1, 29 KOs) didn't flinch while a succession of opponents came and went in recent weeks.
Veteran star Paul Williams accepted the bout just a few days before he was left paralyzed in a motorcycle accident, and James Kirkland declined the shot because of a shoulder injury and gripes about his purse. Ortiz then was promised the fight with Canelo, but his loss - and the broken jaw delivered by Lopez - knocked him out of the running.
The door was open for Lopez, who sprinted through it.
"Josesito has earned the right to fight Canelo, and he earned it the hard way - with his fists," Schaefer said.
When Schaefer first suggested Lopez could be a contender to face the 154-pound Alvarez, he raised eyebrows. After all, Lopez is a longtime lightweight who moved up to 140 pounds in 2008, but has never fought above the 144 pounds he weighed against Ortiz.
But Lopez walks around between fights at more than 160 pounds - and his height advantage was obvious in the staredown. Lopez also has plenty of experience against big guys: He has sparred with plenty, including Chris Arreola, the hulking heavyweight contender and fellow Riverside fighter.
Lopez believes he has a shot against Alvarez, who has risen to the top while still learning the finer points of his sport.
"Canelo, he's a champion for a reason, but he's not going to be hard to find," Lopez said. "He's going to be right in front of me all the time, and I can take a bigger guy's punches."
A few hundred fans gathered mostly to catch a glimpse of Canelo, the red-haired Guadalajara fighter with a fanatical following on both sides of the border. Yet many fans also showed up to cheer Lopez, including a couple of guys in wrestling masks who rattled noisemakers for the underdog from nearby Riverside.
Alvarez rejected the suggestion he's in a strange situation fighting an unheralded, upset-minded opponent.
"I think everybody has something to gain," said Alvarez, who turns 22 on Wednesday. "My job is to get ready for whatever opponent I get. I know he won his way into this fight."