VIDEO: Watch John Mayer Surprise Andy Cohen with A Diana Ross Cover on WATCH WHAT HAPPENS LIVE

Singer John Mayer surprises Andy Cohen with an acoustic cover of Diana Ross' "It's My House" in the Clubhouse and John talks about the prep work he did to make this sweet serenade happen on Watch What Happens Live! Check out the performance below!

"Watch What Happens Live with Andy Cohen" is Bravo's late-night, interactive talk show that features guests from the world of entertainment, politics and pop culture. Hosted by Andy Cohen, the series has become a nightly destination for A-listers including Meryl Streep, Cher, Oprah, Jennifer Lopez, Ryan Reynolds, Jennifer Lawrence, Mariah Carey, Will Ferrell and Gwyneth Paltrow.

Whether "Pleading the Fifth" or "Opening The Vault," endless memorable moments have been revealed as host Andy Cohen continues to challenge some of the biggest celebrities and Bravolebrities on the only truly live, interactive series in late night television.