Zac Brown and Keith Urban will serve as presenters at the Grammy Awards on Sunday (Feb. 13) in Los Angeles. Brown is nominated for best country song ("Free"), best country performance by a duo or group with vocals ("Free") and best country collaboration with vocals ("As She's Walking Away" with Alan Jackson), while Urban is nominated for best male country vocal performance ("'Til Summer Comes Around"). Other newly-announced presenters include Eva Longoria, Jennifer Lopez, Ricky Martin, Clay Matthews, Matthew Morrison, Ryan Seacrest, Jason Segel and will.i.am. In addition, Bob Dylan will perform with Mumford & Sons and the Avett Brothers in a special salute to acoustic music. Other newly-announced performers include Dr. Dre and Adam Levine, who will perform with Eminem. All five nominees in the album of the year and best new artist categories will also perform.