Tatum suffered what appeared to be a serious lower leg injury late in the fourth quarter. He writhed in pain on the court, had to be carried off by Celtics staffers and was seen on ESPN’s broadcast riding in a wheelchair after exiting down the tunnel.

"I feel for him," Brunson said. "It's an unfortunate situation for a player like him. The league needs Jayson Tatum. What he's been able to do in his career has been remarkable. He still has a lot to do in his career, meaning he has a lot of time to make an impact and make a name for his legacy. What he's done is special."

The Celtics bid for back-to-back NBA titles officially is on life support after yet another second-half nosedive. Looking to even the Eastern Conference semifinals at two games apiece, Boston instead squandered a 14-point third-quarter lead and a phenomenal performance from Jayson Tatum in a 121-113 loss to the New York Knicks on Monday night at Madison Square Garden.