Jessica's sister beats her to number one

Jessica Simpson's (pictured) little sister Ashlee is tasting pop success for herself.

Her début album, Autobiography, has shocked music industry experts by crashing in at number one on the charts.

That's two weeks running that the American charts have been upset by first-time chart-toppers.

Last week, easy-listening crooner Jimmy Buffett scored his first number-one album on the Billboard album chart.

Simpson's hit début scores a first for the family as her singing sister has never reached number one.

She hit the top thanks to first-week sales of 398,000 copies.

Buffett has dropped to number two on the chart and rock veterans Van Halen have jumped in at number three with a career-spanning hits compilation.