Chris Brown & Dance Crew -- The INSANE Back-flipping Breakdance Battle [VIDEO]

In case you had any doubt ... Chris Brown is one badass back-flipping dance machine -- and he proved it last night at an L.A. nightclub, throwing down some mind-blowing moves in an impromptu breakdance battle ... and TMZ has the footage.

Brown and his dance crew stormed the stage at Beacher's Madhouse inside the Hollywood Roosevelt Hotel ... unleashing breakdance MAYHEM -- and the crowd went wild. You gotta see the clip.