UPDATE 3-Dark horse Kris Allen wins "American Idol"

(Adds comments from Allen and Lambert)

By Alex Dobuzinskis and Nichola Groom

LOS ANGELES, May 20 (Reuters) - Arkansas student Kris Allen won the eighth season of "American Idol" on Wednesday, dealing an unexpected defeat to singing rival Adam Lambert on the most popular U.S. television show.

Allen, 23, who won over audiences with his all-American good looks and by putting his personal spin on popular tunes, appeared shocked as Lambert, a 27-year-old musical theater actor, embraced him after host Ryan Seacrest's announcement.

"It feels good, but Adam deserves this," Allen said. "I don't even know what to feel right now, this is crazy."

A record high of nearly 100 million votes were cast in the finale. The "Idol" win guarantees Allen a recording contract.

A college student and devout Christian from Arkansas, Allen was the more clean-cut of the two finalists.

He often performed with his acoustic guitar, winning praise for rearranging well-known tunes, among them Michael Jackson's "Remember the Time" and Bill Withers' "Ain't No Sunshine."

As recently as last week, Allen was considered a long shot heading into the battle for the top two "Idol" spots, but he wowed the show's judges with his rendition of Kanye West's "Heartless," ousting early favorite Danny Gokey.

Even hours after winning, Allen appeared stunned.

"I felt shocked almost every week that I made it," he told reporters. "To be the American Idol, I'm completely shocked."

Widely considered the frontrunner since early in the season, Lambert dazzled audiences and the show's celebrity judges with his off-the-charts vocal range and dramatic flair.

With his falsetto singing style, black nail polish and daring wardrobe, Lambert earned the nickname "Glambert." Entertainment Weekly magazine even dubbed him "The most exciting 'American Idol' contestant in years."

Backstage, Lambert appeared unfazed by the loss.

"For me it's not really about what happened tonight, it's about tomorrow," he said.

DARK HORSE