Kevin Spacey -- Belts Billy Joel Like a Boss

You've got to check out "House of Cards" star Kevin Spacey honoring Billy Joel with an epic performance of "Piano Man" ... proving he's still got real deal pipes.

Spacey does the classic major justice as part of "Billy Joel: The Library Of Congress Gershwin Prize" concert airing on PBS January 2nd.

Spacey's no stranger to crooning -- he knocked it out as Bobby Darin in "Beyond The Sea" -- now you can see him blow a mean harmonica and sing ... while Joel bangs on the keys.