LOS ANGELES (Reuters) - Teen singing sensation Justin Bieber gave fans an early Christmas present on Monday with the release of a second single from his upcoming holiday album Under The Mistletoe. The single, Chestnuts Roasting On An Open Fire, is a festive R&B ballad on which Bieber duets with his mentor, Usher. The 17-year-old singer previously collaborated with Usher on the single Somebody to Love from his multi-platinum debut album My World 2.0. The new song premiered on celebrity Ryan Seacrests radio show On Air With Ryan Seacrest, and comes a week before Biebers highly anticipated Christmas album is released, featuring collaborations with Usher, Mariah Carey, Boys II Men, The Band Perry and Busta Rhymes.