The post-fight party was pushing past 4 a.m., and over the din of bruised-up boxers and their trainers and their hangers-on all clinking glasses of champagne, frizzy-haired promoter Don King raised the hand of the 16-1 underdog and new WBC welterweight champion to applause.

“Baldomir, Baldomir,” King boomed. “Viva Baldomir!”

It was an unlikely and unimaginable scene, especially considering the unknown and aging journeyman boxer, Carlos Manuel Baldomir, of Argentina, was never supposed to be at the post-fight party in the first place. The way King and so many others had planned it, King was supposed to be raising the hand of his own fighter, Zab Judah, of Brooklyn, who squandered his 147-pound title to Baldomir at the Madison Square Garden Theater on Saturday night.With the major upset loss, the speedy and hard-hitting Judah also likely squandered his multi-million dollar matchup with the 140-pound titlist, Floyd Mayweather Jr.

Now Judah plunges into uncertainty within the welterweight ranks while Baldomir faces a lucrative title defense (potentially with Mayweather) and virtual stardom back in Santa Fe, his hometown in Argentina.

How did it all happen? In a two-decade long career that has gone unnoticed until now, Baldomir was able to do what he has always done against better opponents in their own backyards: flip the script.

“How do you say ‘Cinderella Man’ in Spanish?” Mike Marley, a New York defense attorney and one of Baldomir’s promotional backers, asked. “However you say it, this guy is it!”

Baldomir entered the fight overlooked. In the months prior, Judah paid so little attention to Baldomir that he never bothered to learn how to pronounce his name correctly. In passing, Judah, a prolific trash talker, kept referring to his mandatory WBC challenger as “Baltimore.”When asked to sign one autograph, Judah scribbled “Pretty Girl’s Next,” a tease to his planned and now tabled scrap with Mayweather,who fights under the nom de guerre “Pretty Boy.”

As for Baldomir, he was merely a stepping stone, the tuneup. Judah, 28, took Baldomir so lightly that on the day before the fight, moments after stepping off the scales at the weighin, he looked Baldomir cold in the eyes and offered him a stone-faced guarantee. “One round,” Judah taunted. “I’m gonna knock you out in one round. I promise.”

Clearly, Judah hadn’t done his homework. Baldomir already had a reputation as a professional spoiler. At 34 – his worn face makes him look much older – Baldomir had only been knocked out once,and that was more than a decade ago. His career record was a misleading and lopsided 42-9-6, but Baldomir had not been beaten in his last 19 fights.

Baldomir was hardly a favorite in those matches, and his lack of technique and punching power – he has only 12 career knockouts – do not make him much of a threat. For the last five years or so, he had trekked around the world to take on much younger prospects with unbeaten records and in their hometowns. His purses were so meager that,when added up, they rivaled the cost of Judah’s flashy collection of bling, much of which he wears in his mouth.

To put himself in the position to fight Judah, Baldomir accepted only $15,000 last summer to face another of King’s fighters, Miguel Angel Rodriguez (then 26-1, with 21 knockouts). In that match, which took place in Chicago, Baldomir upset Rodriguez by outworking him to a unanimous decision and earned the top contender slot. Now Baldomir is poised to earn a purse of $1 million or more if he faces off against Mayweather, and potentially more than that if he can secure a match with Oscar De La Hoya, who will fight Ricardo Mayorga this May. (In the Judah match, Baldomir was contracted to earn $100,000, while Judah earned $250,000.)

“Carlos’s primary weapon is heart,” Sean Gibbons, one of Baldomir’s handlers, said. “He’s seen every style. He makes you work every round. And just when you think, ‘Hey, who is this guy? This guy shouldn’t be in there anymore.’ he manages to win again and again and again.”

That’s what happened in his fight with Judah. Despite getting out-pointed and peppered by jabs and body shots through the first six rounds of the match, Baldomir was able to weather the storm. When an opening finally emerged in the seventh round, he took it, and snapped Judah’s head back with a flush right hand to the temple. Judah staggered around the ring and barely survived the round. But Baldomir kept the pressure on, winning four of the next five rounds and securing a close but unanimous decision. The judges final scores were 115-113, 115-112, 114-113.

Afterward, Judah (now 34-3 with 25 knockouts) said he was discouraged when Baldomir absorbed all his best punches, encouraged Judah to throw more, then kept on coming. Baldomir’s rugged gameness defied Judah’s boxing logic.

“The name of the game in boxing is not who can take the most punches,” Judah said. “The name of game in boxing is to hit and not be hit.”

In this case, Judah’s logic was wrong. He also confessed to not training properly and suffering from a swelled head. Explaining the motives conspiring behind his loss, Judah offered a street-inspired analogy.

“It’s like a Rottweiler who got to be too big for the garage. Sometimes you get a dog, and he gets too big for you to control it, and you know, either you tame it or let it go.”

What that will mean for Judah in the future is unclear.

For Baldomir, his story is just getting good. He trained six grueling months for Saturday night’s match,three times longer than most boxers do, and has waited 20 long years for the dreamy moment of taking a world title home to Argentina.

Baldomir said he couldn’t describe the emotions in words. After fighting in so many countries for so long, away from his wife and four children, waiting for his chance to prove himself against a world class fighter like Judah, and then winning it in a time when everyone doubted him, and now having a chance to make his family rich. There were too many emotions to consider, he said.

Then Baldomir took a sip of champagne through his busted-up lips and smiled so wide he seemed to strain the fresh cuts around his eyes.