Jayson Tatum's playoff run is over -- the Celtics just announced he has surgery to repair a torn right Achilles.
The Boston forward sustained the injury late in Monday night's loss to the New York Knicks at Madison Square Garden -- when he went down while trying to leap for a loose ball.
Initially, all of Boston had hoped it wasn't too serious ... but the Cs said Tuesday that Tatum had "successful surgery" on his ruptured right Achilles and will have a lengthy rehab to get back to the floor.