Britney Spears and Pamela Anderson are among the stars at the pre-Grammy Awards party in Beverly Hills.
Britney and Pamela's boyfriend Kid Rock are due to present awards at the ceremony.
Mary J Blige and Nelly Furtado are late additions to the list of performers. Nelly will team up with rock guitarist Steve Vai for a stripped-down version of I'm Like A Bird.
She has also been rehearsing with N'Sync at the Staples Centre in Los Angeles.
Other performers include Alicia Keys, Destiny's Child, Billy Joel and Tony Bennett, Bob Dylan, Dave Matthews Band, India Arie, Outkast and U2.
Also presenting awards are Celine Dion, the Backstreet Boys, Craig David, Elvis Costello, Matthew McConnaughey, Gloria Estefan, Gwen Stefani, Janet Jackson, Matthew Perry and Sheryl Crow.