Allison Iraheta's 'Someone To Watch Over Me': The Story Behind The Cover

Resident rocker chick shows mature side on Rat Pack night on 'American Idol.'

Allison Iraheta has been this year's resident rocker chick on "American Idol," belting out raspy, high-intensity versions of No Doubt's "Don't Speak" and Aerosmith's "I Don't Want to Miss a Thing." But that was when she was just 16 years old.

Fresh off her birthday celebration the day before, the now-17-year-old Iraheta showed off a decidedly more mature side during Tuesday's

Rat Pack night on "Idol," delivering a sultry version of "Someone to Watch Over Me." (Head here for the story behind

Adam Lambert's cover of "Feeling Good.")

Allison Iraheta's 'Idol' Performances

The song was written by the legendary composer George Gershwin for his 1926 Broadway production "Oh, Kay!," a Prohibition-era musical about a woman who falls in love with a bootlegger and ladies' man. Gershwin's brother, Ira, wrote the lyrics. "Watch Over Me" has since become a jazz standard. It was a favorite of Frank Sinatra's and has been covered by Sting.

"Idol" is, of course, the reigning pop-culture champ on television, and "Watch Over Me" has a long history in film and TV. Its title was borrowed by Ridley Scott for his 1987 thriller starring Tom Berenger.

"Mr. Holland's Opus," the 1995 film about a struggling composer played by Richard Dreyfuss, prominently featured the song. And the sci-fi TV series "Battlestar Galactica" named a recent episode after the track.

In the best tradition of blues singers like Billie Holiday (who also covered the song), Iraheta's "Watch Over Me" was dripping with emotion, tender yet fierce, giving the impression that the cranberry-red-haired teenager truly believed every word she sang.