Knockout marketing

When the arena plunges into darkness, they rise as one: an 8-year-old in a skullcap that says "Punishment," a tourist in a T-shirt that says "Legalized Brutality," a young woman who is being paid $2,000 to wear a bikini and blow kisses to the catcalls. The bass line of a heavy metal song, its lyrics indecipherable at this volume but clearly delineating some manner of rage, compresses 10,863 chests.

It is time.

Once confined to the underground and assailed as "human cockfighting," the savage sport of mixed martial arts -- a spectacle melding ancient fighting tactics with those of a bar brawl -- is poised to go mainstream. Cage-side seats now sell for as much as $1,000. Fights periodically draw more men ages 18 to 34 than anything else on TV. Peddling raw, real violence to a zealous, cutthroat crowd, the sport has become an economic and cultural force through events like this one, held at the Mandalay Bay Events Center on a Saturday night.

Two men, barefoot and slathered with Vaseline, their hands covered in little more than leather wraps, enter a cage at the center of the arena. For five minutes, they kick and punch and lock limbs, trying to land a headlock known in their trade as a guillotine and designed to cut off the blood flow in the opponent's carotid artery.

At the end of the first round, one fighter -- Kenny "KenFlo" Florian, a former college soccer player from Massachusetts -- rests on a stool.

"Be patient!" his trainer tells him. "God will tell you what to do!"

Less than a minute later, Florian crushes his elbow into the right temple of his opponent, Sean "The Muscle Shark" Sherk, a father of two from Minnesota with no discernible neck. Blood begins to spurt from Sherk's head, pooling on the mat, hanging in coagulating strands from the cage fence.

Dana White, the central figure in the sport and the president of its dominant organization, the Ultimate Fighting Championship, is sitting within spitting distance. Glancing repeatedly at a small monitor to ensure that his TV crew is getting the shot, he begins to chew his gum feverishly.

"Jesus!" he says. "It looks like he cut his arm off!"