American Idol winner Carrie Underwood is branching out into acting and will appear in a new film about 19-year-old surfer Bethany Hamilton who had her left arm bitten off in a shark attack.

This weekend will be busy for the star as she is booked to sing the national anthum at the Superbowl on Sunday in Miami, only to fly to Oahu a few hours later to begin work on her first feature film.

The film is set to be released later this summer and Carrie plays Sarah Hill, a youth counselor at Hamilton's church.

Speaking to people.com, Bethany said: "Sarah has been my best friend since I was very young.  "After my shark attack, she always knew what to say to push me on."

Bethany won the special courage award at the 2004 Teen Choice Awards.