It's amazing how long eight seconds can last. Long enough for a bull to lift its dense body six feet off the ground a dozen times; long enough for it to whip its flanks left, then right, then left, all the while making roundhouse kicks and fades. Spit slings through the air, some from the bull, some from the rider. Rider and bull become one, a man-headed minotaur leaping five feet off the ground right before it breaks apart. Part of your brain recognizes this merging of man and beast. The rest of it, however, perceives only an electrified blur, and you wonder how the judges see anything at all.

The arena in Billings, Mont., blazes with white lights. Crowd-roar rains down as the man floats in the air, no part of his body touching the bull except for his face, which slams into the beast's reared-back forehead. A crack visibly arcs from the rider's spine to his boots. He sails off and lands on his ass in dirt clods, and instantly scrambles to his hands and knees and pitches into a sprint. He doesn't even glance back as the 1,800-pound animal bears down on him.

Three bullfighters intercept, flummoxing the animal, drawing its bead from the rider who flies up the racks. The bullfighters -- that is what they are called here, not rodeo clowns -- look like rugby players. They wear shorts, shin guards, athletic shoes. Three is the ideal number in this swift tag-team. They dance on their toes, driving the bull in mad circles. One gets the seat of his pants caught on a horn (its point filed to the regulation size of a 50-cent piece) as another slaps the bull on its rump, whirling it around. Everything happens in-close, like a prizefighting brawl. The movements are so fast, so expertly timed, they are over by the time they register.

It ends suddenly. There is a standoff, the bull facing one of the bullfighters, a man with a crooked face, his bones broken and grown back together in a lopsided, but curiously handsome way. The bull is big and rank. The man is relatively small but stubborn, glaring impatiently. He points at an open gate and says, "Go."

The bull snorts in reply and turns into the pens. The gate slams behind him.

This is not the rodeo. This is the Professional Bull Riding circuit, and the stars of PBR are bull riders, a far more diverse crowd than your classic rodeo cowboys. Some are born cattlemen, while others have never even been on a horse. There are soft-spoken rookies, men with chronic limps, cocky Marlboro types, kids taking breaks to play on Gameboys, and top-scoring Brazilians with their own riding style, who generally keep to themselves, speaking Portuguese with hardly a word of English. What began as a traditional Western sport has gone global in every possible way -- ranching culture on steroids.

Zack Brown is 29 years old. He sits alone on a metal folding chair working his bull rope, preparing for his ride. This is the rider I have chosen to follow, not because I think he will win the championship, but because he is the easiest one to talk to, unassuming and unrehearsed, an intriguing combination of laid-back and shrewd.

"After enough riding, it becomes muscle memory," Brown says in a relaxed, subtle drawl. "You click on your subconscious instead of consciously trying to do this or that." He snaps his fingers: "Then everything starts going your way."

A compact 5-foot-8, Brown has an assured calmness about him. Maybe it's because he grew up in Southern California and Hawaii as a skateboarder and then a surfer, and only later took to bull riding. Or maybe it's because he got his guts stomped out in 2006 here in Billings. A 2,000-pound bull landed square on his abdomen with its hooves, rupturing his innards and filling him with blood and stomach fluids. He was in intensive care for weeks, a powerful dose of humility for anyone.

Even though Brown had a fast-paced career before that -- he was PBR's rookie of the year -- he quit the sport. He was too jittery, he says, lost his motivation. But after a year or so off the circuit, he began to miss the competition and sense of urgency -- he talks about it like an addiction. After a while he started doing small bull-riding events on the side. Now, after a rapid rise through the ranks, he is back in the top circle.

"I like the rush," Brown says. "It makes me feel more alive. I get bored pretty easy."