THE NEXT ACTION HERO by Corey Levitan Hasta la vista, Ah-nuld. When "The Scorpion King" opens Friday, the 20-year reign of a certain 50something movie star is likely to terminate. Hollywood is already abuzz about how indisputably the "Mummy" prequel establishes World Wrestling Federation champ The Rock as Hollywood's premiere action hero. The first journalists to screen the movie in L.A. last week were stunned by the 29- year-old newbie's screen presence. "He's BETTER than Schwarzenegger," raved BBC Radio correspondent Gayl Murphy. "Arnold was never a sexy daddy. He was the guy that the guys liked. But The Rock is a heartbreaker. He's got the moves and really uses his body. "And he's terrific in the role." "He translated well into the action-hero mode," said Scott Bowles of "USA Today." "And good actors can't always do it. Guy Pearce couldn't do it in 'Time Machine" and Chris O'Donnell couldn't in 'Vertical Limit.' "He certainly has that presence." Rock-solid notices are also pouring into Hollywood hipness barometer AintItCoolNews.com. "People really seem to like this movie," says Harry Knowles, the website's founder. In a shock bigger than any gauze-wrapped digitized skeleton could provide, "The Scorpion King" turns out to be pretty damned good. More like an "Indiana Jones" than a "Mummy" franchise, its minimal special effects never substitute for plot or character development. "I didn't want to do the film if it was 'Mummy 3,'" says director Chuck Russell, who grabs the felt chair from Stephen Sommers. "The fact that this film has a unique tone from the 'Mummy' movies is very important to me." The Rock plays the Scorpion King 5000 years before Brendan Fraser encounters his silly ghost at the end of last year's "The Mummy Returns." He's known simply as Mathayus, a very human assassin desperate to rid ancient Gomorrah of its evil ruler (Steven Brand). Any doubts that the 6'5", 250 lb. king of the ring could pull off toplining a $60 million motion picture are dispensed with as quickly as Mathayus' enemies. The Rock frightens as effectively as Schwarzenegger in 1982's "Conan the Barbarian," while charming like the man in 1991's "Terminator 2: Judgment Day." "Good Lord, are you going to kill me?" a terrified elderly bystander asks Mathayus at one point. "Maybe later," Mathayus responds, in a way that lets you know he would never do that. The Arnold comparison is unavoidable. Both men are exotic foreigners to the Hollywood scene, disregarded at first as muscle-headed doofuses, who prove that they have much more to offer. "It's worth comparing," says Russell, who directed Schwarzenegger in 1996's "Eraser." "They're two entirely different people, but they both have a sort of amazing background athletically. And, if I can risk being corny, they're both champions." Both also remind us that burliness and burlesque are not mutually exclusive. Like Schwarzenegger, The Rock has a keen sense of himself, and how funny he is playing against type. "Ow!" he screams like a schoolgirl in the new film, after his arm is only slightly scraped in a swordfight with comely sorceress Cassandra (Kelly Hu). "There's a real sense of knowing that he's in an action scene while he's in it," says "The Scorpion King's" producer, Kevin Misher. "There's a wink and a nod that we know where we are." Where Dwayne Douglas Johnson has been most of his life is wrestling. His Samoan mother, Ata, was the daughter of the legendary Peter Maivia, known on the mat as High Chief. Dwayne's African-American dad, Rocky, was also a wrestling champ. Home life was about as normal as it is for "The Osbournes" -- without the humor. Surrounded by professional-wrestling family friends, the Johnsons lived all over the map before settling in Bethlehem, Pennsylvania. Dad squandered the family savings and became a drunk, according to The Rock's 2000 autobiography, "The Rock Says..." The house and car eventually disappeared. But soon, so would young Dwayne, who had a promising alternative career on the high- school football field. It took him to the University of Miami on a scholarship, where he ended up majoring in Jack Daniel's (actually: criminology) because All-American defensive tackle Warren Sapp already occupied his position. The perpetual benchwarmer raised hell as effectively as he would one day raise his right eyebrow. Once, he vented by attempting to yank out a teammate's tongue, hinting at the greatness to come. Dwayne gave the Canadian Football League a failed shot following his 1995 graduation. But, much like Michael Corleone, the family business pulled him back in. Borrowing names from his father and grandfather, Rocky Maivia (or The Rock, for short) became not only the youngest WWF champ ever at 26, but also the most frequent (6 times). So astronomical was his rise that his catchphrases ("Do you smell what The Rock is cooking?"/"Know your role, Jabroni, and shut your mouth!") began to escape the ring and threaten popular culture. The Rock wanted to hurry the process, of course. So he asked WWF owner Vince McMahon to help make him a household name. Seeing the opportunity for wrestling cross- promotion, McMahon pitched "Saturday Night Live." The Rock hosted in March 2000. "Everybody knows the rigors of pulling off that show and we've all seen people fall flat on their face," says Misher. "But he was able to pull it off, and in such a winning way. "It was the combination of seeing a guy who looks like that, and can perform like that -- and seeing the sense of humor he has -- that convinced everybody." Well, not everybody... Russell, who took on "The Scorpion King" with The Rock already weighing it down, at first wrestled with doubt. The Rock's only previous screen experience was 5 minutes at the beginning and end of "The Mummy Returns," during which all he did was fight and yell in Egyptian. "I'd ask myself, 'Is this an opportunistic celebrity who's gonna jump right back to wrestling and not make it to my rehearsals?'" admits Russell, who is famous for his gut instinct about untried actors. (He introduced both Jim Carrey and Cameron Diaz to movie stardom in 1994's "The Mask.") "But The Rock so impressed me with how serious he was about acting and how willing he was to do everything -- from improv, study work and working out the chemistry with the other cast members -- that I was very comfortable by the time we started," Russell says. The Rock -- who received $5.5 million for "The Scorpion King," a hefty bulk-up from his $500,000 "Mummy Returns" pay stub -- prepped for two weeks with renowned acting coach Larry Moss. He was recommended by Michael Clarke Duncan, trained by Moss for his Oscar-winning turn in "The Green Mile." "When he came back, he was totally different," says Duncan, who also stars in "The Scorpion King." "The Rock was able to bring his emotions up and do a lot of other things that maybe he wouldn't have been able to do had he not studied with Mr. Moss." The Rock -- who splits his time between L.A. and Miami, home to his wife, Dany Garcia, and their baby daughter, Simone Alexandra -- is really a sensitive guy at heart, says Duncan. And while you don't get that from his loudmouthed wrestling caricature, he is able to radiate some of that on screen. "He's a little softie," Duncan says. "He's no Rock." As proof, Duncan recalls what happened after The Rock's right elbow accidentally rendered him unconscious during a fight scene. "I said, 'I'm gonna play on this thing,'" says Duncan, who wasn't really hurt. "So I took one of those cotton balls, dipped it in fake blood and stuck it up under my lip." Duncan asked The Rock if he looked OK for his close-up, cracking a big red smile. "He's like, 'MICHAEL!! I'M SO SORRY!!'" Duncan says. "And he starts getting ready to cry." All this, plus, the guy does his own stunts. "You don't have to cut away and put in a stunt double and suddenly you're looking at somebody's back as they go up a cliff," says Misher. "We had to hold him back from doing more!" Of course, now that the word is out, everyone wants a piece of The Rock. He's already been signed for his next movie, tentatively titled "Helldorado," an action flick set in the Amazon, in which he will play a bounty hunter. Shooting begins this fall. So how does all this pressure sit on the man? Is he comfortable knowing that he alone will probably transform you-know-who into the NEXT-TO-last action hero? "Oh yes, Rock, yoo-arr do-eeng fan-tah- steek, yah!" says The Rock, performing a perfect Schwarzenegger impression for The Post at the movie's L.A. junket. In real life, the two are friends. After Schwarzenegger cracked his ribs in a motorcycle accident last year, The Rock sent him a tricycle in the hospital. And Arnold came to the set of "The Scorpion King" to wish its star well. "The comparisons have been great," The Rock says. "But his shoes are really big to fill. "Not that I'm not confident or ambitious, but I'd prefer just to make my own path and do my own thing."