Turns out it TOTALLY happened ... and Donnell not only told the tale to TMZ Sports when we got him out at the Hollywood Improv Tuesday night -- he also provided VIDEO EVIDENCE!
It went down at a charity game in DC a few years back when Rawlings stole the ball from KD, then pushed the rock hard up the court to drain a smooth three.
Almost as dope as the moment itself? Donnell says he ran into Durant during All-Star Weekend in New Orleans and brought it up to him, and KD totally remembered.
Check it out below ... sorry we ever doubted you, Donnell.