VIDEO: Josh Groban Talks Working with Barbra Streisand & More on WATCH WHAT HAPPENS

Josh Groban was a guest on last night's WATCH WHAT HAPPENS LIVE and revealed which singer intimidates him most. Later, he talks about working with Barbra Streisand when he was an 18-year-old "kid" and pleads the fifth when Andy Cohen asks him if he ever dated singer Katy Perry, saying that they are close friends. Watch clips from the appearance below!

Multi-platinum recording artist Josh Groban released his new album "Stages" on April 28th, 2015, via Reprise Records. The album is a collection of some of the greatest musical theater songs of all time

Recorded with producers Humberto Gatica and Bernie Herms in both Los Angeles and London's Abbey Road (with a 75-piece orchestra), Stages features songs from LES MISERABLES ("Bring Him Home"); Rodgers & Hammerstein'sCarousel ("You'll Never Walk Alone"); Stephen Sondheim's Sunday in the Park with George ("Finishing the Hat"), Sweeney Todd ("Not While I'm Around"), and Into the Woods ("Children Will Listen"); The Fantasticks ("Try to Remember"); A Chorus Line ("What I Did For Love"); Andrew Lloyd Weber's Phantom of the Opera ("All I Ask of You"), The Wizard of Oz ("Over the Rainbow"), and others.

Stages also features duets with Audra McDonald sings on "If I Loved You" ("in my head I heard her on this and to sing it in the room with her was a dream come true"); and trumpeter Chris Botti plays on "Old Devil Moon" ("he plays with such control and expressiveness").

Photo: Charles Sykes/Bravo