Nobody needs to tell this crowd to get ready to rumble. As Ziggo and The Executioner square off in the four-cornered ring, fans of both fighters join in the boisterous countdown: "Five, four, three, two, one . . . Kick bot!"

The fighters head straight toward each other, feign blows, and then attack. But what you hear is not the dull thud of boxing-glove leather against flesh. It’s the noisy slam of steel against steel. This is Battlebots, a mechanized slugfest in which radio-operated robots set out to destroy one another. Imagine a Ginsu commercial that has run amok. As Ziggo and The Executioner collide, the crunching sound reverberates throughout the Pyramid arena in Long Beach, California. Seconds later, there's an awful, paint-peeling screeeeeee.

That's when Ziggo moves in for the kill.

All day long Ziggo has been scattering robot parts around the ring. Looking like an upside-down wok, the robot favors a simple strategy: spin really fast, crash into opponents, and rip them to pieces. But it might take a lot more than that to bring down The Executioner, an evil looking machine outfitted with a large chain saw.

Ziggo sticks to the tried-and-true. Rotating like a supercharged margarita mixer, it suddenly pins The Executioner to the wall. Then the Executioner's chain saw whirs into action with a sickening roar. Now it's time for The Executioner to inflict some damage–yet the robot seems helpless against the onslaught of Ziggo's relentless spinning. A few minutes and a couple of thousand rotations later, Ziggo literally wears The Executioner's chain around its neck. The crowd erupts in foot-stomping applause, demanding blood and getting motor oil.

"This is the last kind of violence that's completely P.C.," says Reason Bradley, 27, a robot builder from Sausilito, California "Yet there's absolute destruction and mayhem."

Fortunately, Battlebots' mayhem is reasonably controlled. The bots duke it out behind four 16-foot walls made of clear, bulletproof polycarbonate. The ring has been designed with a number of treacherous hazards–giant nails stick out from the sides, spinning blades rise out of the metal floor. But the robots take all the risks; their owners crouch safely just outside the protective walls, operating radio controllers equipped with joysticks or small steering wheels.

Robots slated to fight in of official competition this weekend must weigh in at no more than 210 pounds. Other than that, they run the gamut–from K.I.S.S. (Keep it Simple, Stupid), a down-and-dirty street fighter made of scavenged highway signs, to Biohazard, whose sleek titanium body has the clean lines of a Jaguar. Built at an estimated cost of $70,000, Biohazard is the sport's reigning heavyweight champ, the one robot everyone wants to beat.

The robot builders are a similarly varied bunch of guys. There are professionals like Mark Setrakian, who builds special-effects models for Hollywood movies and keeps his fingernails sharply filed so they can double as tweezers or screwdrivers. Setrakian came here with a 400-pound monster that resembles a gigantic steel insect. (Well over the weight limit, it'll fight an exhibition match only). Many others are hobbyists who have cobbled together crude fighting machines in their garages.

Standing near the rear entrance of the arena, a "pit" where robots are being repaired and tested, Reason Bradley takes in the scene with a look of pleasure. He has high hopes for Rhino, a bot he created with the help of three partners. At first glance, Rhino looks like little more than a shiny box. Then you notice its built-in weapon: a metal battering ram about an inch thick.

Powered by compressed gas– "one of the most dangerous things to work with," Bradley notes–the ram can strike with 3,000 pounds of force, enough to penetrate a steel wall. Now, that's a punch.

For hard evidence of how much damage Rhino can inflict, just look at S.L.A.M. Like K.I.S.S., it was built by Steve and Lowell Nelson, a father-son team from Reno. S.L.A.M. (Steve and Lowell's Attack Machine) is a squat metal cylinder powered by an old chainsaw engine. It looks as tough as nails, but during an earlier bout, Rhino punched a series of holes in S.L.A.M., which ultimately lost the fight when its battery got knocked loose.

"Yeah, S.L.A.M. ain't a virgin anymore says Steve Nelson, 38, while his father fills the robot's tank with gasoline from a dish-detergent bottle. "We'll fix the battery and leave the holes. You have to show your robot's battle scars."

Like many weirdly cool developments in High Tech, the birth of battling robots can be traced to Japan, where they have been going at it since the 1980s. The fighting machines first appeared in America in 1994 as part of an art show, and that eventually led to Robot Wars, an annual competition held in San Francisco. Then, because of some bad blood between organizers of that event, a renegade group moved the action to Southern California, where 75 robots will compete for more than $28,000 in prizes this weekend.

The atmosphere inside the arena suggests a cross between pro wrestling and a rock concert. Battlebots is soundtracked with a booming mix of hip-hop, big-beat electronica, and rock 'n' roll. Many of the robots have names that could easily be adopted by speed-metal bands: Kill-O-Amp, Ankle Biter, Nightmare. An M.C. in a tuxedo, his neck as thick as Vince McMahon's, leads the countdown before each bout and provides light commentary (''Ankle Biter says he likes the taste of minivans, but the bumpers give him gas"). But the robot builders–who come from all over America and as far away as England–approach this as a serious sporting event. The double-elimination tournament will finish with a single winner in each of three weight classes. The weekend culminates with the Robot Rumble, a no-holds-barred contest in which all the bots have it out, demolition-derby style.

Now the Rhino crew take their place just outside the ring. Reason Bradley takes the radio controller, while one partner, Alexander Rose, mans a separate electronic device that operates Rhino's battering ram. Inside the ring, Rhino is going up against Vlad the Impaler, a tanklike machine with two bazooka-shaped hole punchers protruding from its front.

The fight starts slowly, with both bots playing defense, cagily keeping their distance as they size each other up. The crowd grows restless. Without warning, Bradley sends Rhino on a beeline toward Vlad. A red laser beam pinpoints the spot where Rhino's ram will make contact.

Operating the ram, Rose waits for a clear shot. Then he lets it rip. There's a loud hiss–the compressed gas that fuels the ram being expelled–as Vlad absorbs the first blow. Vlad looks rattled. Emboldened, Rhino charges again. The ram strikes several more times before Vlad finally wheezes in defeat and Rhino is declared the winner. Bradley sends his robot on a joyful spin–the Battlebots equivalent of an end-zone celebration dance.

But don't get the idea that Rhino has a tender side. Like all of the fighters at Battlebots, it has been designed for one purpose: to destroy other robots. Back in the pit, Rhino's creators repeatedly implore people not to stand directly in front of the ram. "This is something that the human body can't tolerate," says Rose. "We treat it the same way we would treat a loaded gun."

Ian Lewis might have benefited from that wisdom. He came here from England with Razer, a gnarly-looking machine notable for the big steel hook rising out of its base. As a traveling companion, Razer proved temperamental. "The robot reversed into me," says Lewis. "Its tail went straight through my boot, into the toe, and out the other side. "He holds up the punctured boot. "Razer lost its signal and got tuned into another frequency," he explains." It only takes a millisecond before this thing comes at you so fast that you can't get out of the way."

Back in the ring, Killerhurtz–another English import–is caught at a disadvantage. The robot is designed to chop down the competition with a giant hatchet, but its owner, John Reid, left a crucial component home in Oxford. Unable to attach the shiny hatchet properly, Reid must send Killerhurtz into battle armed with only a bladeless rod. One look at Nightmare's giant buzz saw, and you know where to place your bet. Just seconds into the fight, Nightmare's rotating blade goes to work. Then, oddly, wood shards begin to fly as sawdust piles up between the two robots.

In the end, Reid emerges victorious, rolling his winning robot away from the ring. "We were terrified of that saw," he explains, "so we came up with an idea–sacrificial bumpers." Reid then describes a strategy as innovative as Muhammad Ali's famous rope-a-dope technique: The other robot hit these wooden bumpers," be says, grinning at his own ingenuity, "and used up all of its energy, sawing through them."

Its late afternoon on Sunday, the final day of Battlebots.

It's late afternoon on Sunday, the final day of Battlebots. A large man walks by carrying a Styrofoam coffee cup filled with steaming liquid nitrogen. Burning electricity scents the air. Some robots have been reduced to scrap, and the Rhino crew is all but finished. The guys whose bots have been knocked out of the running have turned their focus to the Robot Rumble, where they can wreak havoc on the machines that humiliated them in official competition.

Biohazard, meanwhile, keeps advancing steadily toward the championship that everyone already knows will be his. The Mike Tyson of robots doesn't seem all that fierce– "Most of the other robots look scarier than mine," concedes its owner, Carlo Bertocchini–but its boxy, low-to-the-ground design makes it difficult to damage. Biohazard's main offensive weapon is "the arm"– a cranelike claw that unfolds from inside its base. This afternoon, the titanium champ uses that tool to lift a challenger off the floor, carry it around the ring, and deposit it onto one of the spinning blades built into the floor of the ring. Another easy win.

Afterward, Bertocchini walks Biohazard out of the ring, then stops to observe a test-run of Nightmare's buzz saw, which is said to rotate at nearly 300 miles per hour. "Nightmare could definitely do some damage to my robot," he admits. But Bertocchini remains coolly confident in his own machine. "If somebody hadn't seen Biohazard fight before, they'd probably figure that it couldn't win." he says. "Then they would see the arm come up."

There's no need for him to say what happens next. Everyone here knows Biohazard's signature move: using the dreaded arm to flip a robot onto its back so that it's immobilized, helpless, but not too badly damaged (Bertocchini likes to call his creation "a kinder, gentler robot"). In the last bout, Biohazard enter the ring with Killerhurtz and does it again– smoothly executed flip-over that ends the fight. Once again, Biohazard is the heavyweight champion.

But that's okay because now everyone has a chance to get even–in the Robot Rumble. A few dozen robots are rolled in for the final free-for-all. After the countdown, the ring becomes a mess of roaring, creeping, bashing metal. Biohazard is dragging around The Mauler, which has vainly tried to live up to its name. Soon two other robots–Tazbot, a mutant variation on a lunar exploration module, and Bad Boy, a pickax on wheels–also go work on The Mauler. Razer, digging its sharp beak into a cylindrical machine, looks as though it's opening an enormous can of tuna. "Say goodbye to your robot," one of the guys on the sidelines says grimly.

By now, the robots seem to be colliding with one another at random. Smoke pours out of one, and it's promptly yanked from battle. Rhino gets shoved against a wall and loses its spin. Others are sputtering and worn out, like boxers in the 12th round. One robot seems to be spinning aimlessly, like a heavyweight who has taken too many shots to the head.

Motors die down, the house lights come up, and the robots are carried from the ring. Already there is talk of the next Battlebots, which will he held in Las Vegas and aired on Pay-Per-View January 29. As the robot builders pack up their machines, they talk about getting another shot at Biohazard, which made it through the final melee with scarcely a scratch.

John Reid, whose robot finished second despite its disabled hatchet, is preparing for the long trip back to England when someone asks if he'll make it to Vegas later in the year. Standing proudly next to Killerhurtz, he surveys the wreckage around him. "I just might have to," he says with a smile.

Then he runs his fingers along Killerhurtz's unused hatchet blade, thinking happy thoughts.

You can buy a robot kit at a hobby shop. But it's more fun-and a lot cheaper, to build one from scratch. Steve Nelson kicked bot at Battlebots with K.I.S.S., a pretty killing machine that he constructed for less than $1,000. Here's how:

BE A SCAVENGER "The engine, the transmission, the rear-axle differential,, and the front axle for steering all came from a lawn tractor that someone gave me," Steve says.

GET FRAMED "I bought 1-1/4 inch steel tubing ($30) for the frame and chassis and welded the whole thing together. For the transmission plate, I got a piece of T-6 aluminum ($18) from the salvage yard. It used to be part of a sailboat."

BUILD SUSPENSE "I used a piece of steel tubing for the front suspension and wound up with something similar to what you'd see on a GoKart," says Steve. The inflatable pneumatic wheels are often found on handcarts. Total cost: $20.

TUNE IN The High Tech Prism 7X radio control ($350) from Tower Hobbies (www.towerhobbies.com) offers the most channels for the money. "It also has a thing called PCM [post-code modulation], so it doesn't get confused with other radio signals, Steve says "Plus, Tower Hobbies has an online tutorial."

DEVELOP A PATTERN Steve cut out a cardboard pattern for the body, then picked up some aluminum street signs at a wrecking yard. "We followed the pattern, put it together with screws, then had it welded." he says, emphasizing that it's vital to cover the wheels: "Otherwise, anyone with a weapon will clip your wheels off or get underneath and turn your robot over." Cost: $250 (plus $40 for materials).

LITTLE THINGS ADD UP A whole bunch of smaller parts get the job done. "For example, we had to purchase a clutch and bearings and an $80 speed controller." says Steve.

WARNING! WARNING! Work refreshed- and carefully. A tired robot maker is bound to put parts on backward and hurt the electronics. "At that point you begin using a tot of colorful adjectives," Steve says, adding one ominous reminder: "Remember that you're creating a monster. You can never be 100-percent sure what will happen."