The Recording Academy said Wednesday the duet will be available for download at iTunes.com/Target following the show, with all proceeds going to the American Red Cross to benefit earthquake relief efforts in Haiti.
The 52nd annual Grammy Awards will air live Sunday on CBS from the Staples Center in Los Angeles.
Music's biggest night will also include performances by album of the year nominees Beyonce, the Black Eyed Peas, Lady Gaga, the Dave Matthews Band and Taylor Swift.
