Nobody loved Trae Young's game-winner more than his dad ... because Pops celebrated his son's huge feat like a little kid -- and the awesome reaction was all caught on video!!!
Just seconds after the Atlanta Hawks superstar plunged a dagger into the Knicks by hitting a floater with .09 ticks on the clock ... Trae's father, Rayford Young, called out to his boy.
"Trae! Trae!" Rayford yelled.
And, as soon as Trae acknowledged the love -- Rayford went crazy!!
Check out the clip ... Dad couldn't have been proud -- smiling, laughing, slapping hands with friends and family, and even letting out a "F*** yeah!