As if gambling with their blood, retinas and brainwaves weren't enough, Felix Trinidad and Ricardo Mayorga agreed to an additional side bet.

A nice, round $100,000 from the loser's purse was payable the winner of Saturday night's 12-round middleweight showdown in Madison Square Garden. Although contract probably wouldn't skirt New York laws, the fighters signed them anyway to ensure the loser wouldn't welsh.

Mayorga already had his money spent. He proclaimed before the fight he was going to buy a limousine.

“The limousine he wanted to win with my money,” Trinidad said through an interpreter early Sunday morning, “now he has to buy just a little car.”

Mayorga left the Garden in neither a limo nor a carrito, but rather an ambulance. He was in a daze when he was whisked away to Bellevue Hospital for evaluation after Trinidad floored him three times in the eighth round to win a humdinger of a brawl.

At a time when boxing is desperate for the emergence of a bona fide superstar to replace the long list of recent fallen warriors, Trinidad provided the next best thing: the return of an elite fighter after a two-year retirement.

“Tito, Tito, you are my shining star,” promoter Don King melodiously offered. “Don't you go away.”

Trinidad looked as though he hadn't been out of the gym for a day. He carried the same, slender physique. There was no rust, no corrosion or even a speck of dust on his gloves. He unleashed a prodigious assault, and Mayorga valiantly weathered it for seven rounds until his body could stand no more.

“I was strong in the ring, and I felt very comfortable,” said Trinidad, fighting for the first time since he stopped Hassine Cherifi in May 2002. “I expected a tough fight and Mayorga did not prove me wrong. He has an incredible chin and great power.”

The matchup made for riveting theater. The 17,406 fans in attendance were forcefully behind Trinidad. Puerto Rican flags rippled. Cheers of “Ti-to! Ti-to!” thundered. The staunch loyalists even booed the Nicaraguan national anthem.

The fans stood for most of the bout. The proud fighters wouldn't give them a chance to sit.

Trinidad and Mayorga immediately went after each other from the opening bell, and it had little to do with their desire to win the vacant WBA North America and North American Boxing Council belts. Trinidad's punches were thrown with dart-like accuracy, while Mayorga cocked his shots from somewhere near the fifth-floor concession stands.

Mayorga exhibited no fear of Trinidad's storied power and was intent upon testing it straight away. The chain-smoking swashbuckler with died-crimson hair imparted that infamous go-ahead-I-dare-ya pose, dropping his gloves and inviting Trinidad to take his best shot or two. The psychological tactic demoralized Vernon Forrest when they first met in January 2003 because Mayorga didn't blink. The fight essentially was over.

This time, Trinidad hammered his defenseless foe with a pair of flush left hooks. Mayorga seemed to enjoy it — for about three seconds. Trinidad followed up with a remarkable barrage, and it was a wonder Mayorga was still standing at the bell.

Trinidad won the second round just as easily, uncorking skull shot after skull shot. Mayorga, however, kept coming forward and landed enough punches to maintain justifiable respect.

Mayorga caught his first break in the third round, when he landed a right to the back of an off-balance Trinidad's head. Trinidad awkwardly lurched forward and instinctively put his left hand down to keep him from falling. As soon as the glove touched the canvas, referee Steve Smoger called a knockdown. The fight was even after three rounds.

Trinidad took the fourth round easily enough, but his best round yet came in the fifth. He peppered Mayorga with all manner of punches throughout, but with about 35 seconds left in the round Trinidad let loose a series of scalp seekers. Blood drained from below his left eye.

Mayorga didn't go down in the fifth round, but he dominated so thoroughly it should have been scored 10-8. Judges Guy Jutras, Steve Weisfeld and Fred Ucci assessed accordingly, but Ucci reconsidered and scrawled a 9 over his 8.

“I came out for this bout in better condition,” Trinidad said. “It was a tough fight. I have to say that Mayorga is a real hard, hard fight. He hits hard, takes a lot of punches. But I came to win, and when I put my hands on my opponents, I make him feel it.”

Trinidad exalted the crowd at the start of the sixth. He stood gallantly in his corner before the bell and punched his shoulder in salutation. Across the way, Mayorga slouched on his stool and somehow gathered yet more strength.

Mayorga got lucky again with about 40 seconds left in the sixth round, when a Trinidad left hook struck him in the right quadriceps. It's unclear if Mayorga sustained a deep bruise or a charley horse, but Smoger called time and allowed the hobbled fighter time to recover. The breather seemed to boost Mayorga, who closed the round solidly.

Mayorga jumped on Trinidad to begin the seventh round and appeared to be gaining momentum, but Trinidad went wild over the last 55 seconds. Mayorga again was reeling at the bell.

Trinidad, after popping Mayorga's noggin all night, closed the show with body blows. A searing left sent Mayorga to the canvas with 1:22 left in the round. Another gut shot ignited a combination that dropped Mayorga again about 30 seconds later.

“The body shots changed the history, and a valiant Mayorga had no option but to go down for the first time in his career,'' said Trinidad's father and trainer, Felix Sr.

No single punch ended the fight. Mayorga himself bailed out and dropped to all fours with 21 seconds remaining in the eighth round. It was all he could do to prevent Trinidad from continuing a vicious cranial assault.

“I felt good about my performance, but my eye swelled up and I couldn't see some shots,” Mayorga said through interpreter.

Mayorga was asked if he thought he had hurt Trinidad when Smoger called the third-round knockdown. In no-excuse, true warrior fashion, Mayorga replied “No” before he was directed from the ring and into the awaiting ambulance.