D'Angelo Russell's impromptu Lionel Messi impression just set him back a wad of dough -- the Lakers guard was just fined $15k for punting the rock into the stands after Saturday's double-overtime win over the Warriors.
The NBA just handed down the punishment on Monday ... with the league's executive VP Joe Dumars announcing the costly penalty.
The moment happened after the final buzzer of the second extra period ... when Stephen Curry heaved the ball three-quarters of the court in a last-ditch effort to win the game.
As the ball made its way back down to earth, Russell ran onto the hardwood to celebrate the 145-144 win ... kicking the rock into the first few rows of the arena in the process.
While it seemed like the 27-year-old was just trying to have some fun, the league decided it was a finable offense nonetheless.
It's a bummer for D-Lo, but it's just a drop in the bucket for the guy -- he's made over $155 million on the court over the course of his career ... including $17 million this season alone.