Rihanna has scored a second week at the top of the U.S. pop charts, despite a challenge from American Idol runner-up David Archuleta.

The newcomer's single "Crush" becomes the Billboard Hot 100's highest chart debut in more than 18 months after rocketing to number two thanks mainly to 166,000 first-week downloads.

Archuleta's hit just didn't have the power to topple Rihanna's Disturbia.

Forever, by the R+B star's boyfriend Chris Brown, slips to three on the new chart and Katy Perry's I Kissed A Girl falls to four.