HOLLYWOOD-- He looks innocent enough, as he reclines by his hotel pool, all skinny limbs, rumpled jeans and sweater, his big doe eyes peeking out from beneath strawlike strands of disheveled brown hair.

If a crime had been committed anywhere in the neighborhood, rest assured, this polite 26-year-old Australian couldn't possibly have done it. He seems so calm, so quiet, so sweetly unobtrusive.

A year ago, however, this mousy man - Craig Nicholls, frontman for iconoclastic Sydney rock combo the Vines - was raising so much hell, he might have been some escapee from a mental institution. And everywhere he careened on tour, folks got more than a little nervous.

An Australian interview with Britain's NME found him hurling fish sandwiches out the tour van window at the windshields of other drivers.

A coveted booking on Jay Leno's "Tonight Show" short-circuited during afternoon rehearsals, when Nicholls trashed the NBC studios set, and an appearance on "The Late Show With David Letterman" ended similarly, with the singer backflipping onto Letterman's couch, hurling his guitar at drummer Hamish Rosser's head, then pushing himself across the carpet, screaming.

Music-biz insiders began whispering it at first, then talking openly about it: Nicholls, despite the songwriting skills he displayed on the Vines' platinum-plus Capitol debut, "Highly Evolved," was just plumb nuts.

Surely the guy wouldn't last long enough to record a second album. Lo and behold, the quartet just released its sophomore salvo, "Winning Days," a remarkably solid set that finds Nicholls - dare we say it? -maturing, rocketing past the Nirvana/Beatle-isms of "Evolved" into a finely tuned, Kinks-retro chime/snarl.

Opening onto the jagged, stuttery riff of "Ride," the disc bounds boldly through ballads ("Sunchild," "Autumn Shade 2"), sing-song pop ("Rainfall," "Winning Days") and even a little Pink Floydian psychedelia ("Amnesia"). If Nicholls is crazy, he's crazy like a fox.

But get ready to gasp again, people.

Nicholls is now every bit as sedate as his demeanor suggests. He barely remembers those meltdowns that branded him one of rock's rowdiest renegades.

"I've given up drinking and smoking - any kind of smoking," confesses the former pothead, whose dressing-room piles of marijuana were often the size of miniature haystacks.

And for any past wrongdoings, he sighs, "I formally apologize - I was probably just out of my mind.... A lot of people thought that I was this little monster who'd always be throwing things around. But when you're young, I guess you do things that you just wouldn't do when you're older."

How and why did Nicholls shake his substance abuse? "I really can't remember," he murmurs. "It wasn't a conscious thing - it just kinda happened. I started doing it less and less until I realized that I wasn't doing it at all. And quitting has made me calm down quite a bit, given me a bit more perspective. Looking back, I think I probably had a few mental breakdowns. But for some reason, I feel OK now. Now this is what I have to look forward to," he chortles as his manager brings him a piping-hot bag of Wendy's hamburgers. He spends the next couple of minutes wolfing one down.

Nicholls can't help it. Fast food is in his blood. Five of his teenage years were spent flipping burgers at a Sydney McDonald's (serving dubious delicacies like the McOz, basically a Quarter Pounder with a beet slab slapped on top), where he met a fellow Beatles/Nirvana geek, bassist Patrick Matthews.

Reclusive Nicholls had barely played any local live dates when he and his chum's Vines inked a deal three years ago on the strength of some fiery four-track demos. They went on to hit the U.S. cover of Rolling Stone. It was the first Australian band to receive that honor since Men At Work, two decades earlier.

Did things simply happen too fast for these antipodean naifs?

"Maybe," Nicholls confesses. "It got pretty crazy. And people kept saying 'Oh, are you the next big band?' They were curious about us, but we didn't wanna say 'Don't pay any attention to us - we're junk,' and we didn't wanna say 'Yeah, we're the greatest band.' We just really loved making music. That's why Patrick and I got into it. Still, people didn't know what to think of me - they thought I was an all right singer, but maybe a bit... a bit cocky or something?" 

Or something.

Despite the jarring guitarwork of "Ride" (a blatant homage to Ray and Dave Davies' classic "You Really Got Me"), Nicholls swears he's into nothing "but peace and tranquility now - to me, that's where our music's headed. I've even sensed that I'm getting much more country-rock, but it doesn't scare me. I just think, 'OK - I guess this our next phase.' It seems very natural to me, and now that I'm more mellow, I'm trying to be more thoughtful and considerate."

Even in his songwriting.

Have The Vines gone totally goody-two-shoes now?

Well, "Winning Days" does feature a bratty, spit-vocalled punk anthem called "Fuck The World," one of Nicholls' most maniacal takes to date. And the band is hitting the Warfield on an all-Down-Under tour Sunday alongside fellow rabble-rousers Jet and The Living End.

Nicholls cedes that one of his defining career moments occurred a year ago, mid-tour, when two teenage fans approached him after a gig.

"This guy and girl came up to me and said 'We're really worried about you,'" he recalls. "They'd read some stuff about me in a magazine, but I said 'No, it's all right, I'm OK.'"

Inside, though, Nicholls suspected the kids were right. Now, he realizes that his rollercoaster ride to fame might have actually done him in.

"But I'm always worried that I'm gonna die anyway," he concludes, finishing his fries. "And why? Just because I think life's so great. I mean, it can be so great. I have my off days, but no matter how bad things are, you've just gotta focus on the positive things. Otherwise, life can be really hard."