NBA playoffs: Jaylen Brown's clutch 3 stuns Pacers as Celtics rip Game 1 from Pacers in OT

The Indiana Pacers appeared to have a Game 1 upset in hand.

Jaylen Brown had other ideas.

The Boston Celtics All-Star stunned the Pacers with a 3-pointer in the final seconds of regulation to tie Tuesday's Game 1 of the Eastern Conference finals at 117-117. The game then went into overtime, where the Celtics prevailed, 132-128 to take a 1-0 series lead.

The Pacers led, 115-110 late and appeared to be in control with the ball and a 117-114 advantage with 8.5 seconds left in regulation. But they turned the ball over on a sloppy inbounds pass to breath new life into the Celtics. Brown took full advantage.

With Pascal Siakam in his face, Brown launched a 3-pointer from the left corner that found the bottom of the net as the clock red 5.7 seconds to secure the extra session.

There, Jayson Tatum scored eight points including a 3-pointer with 42.8 seconds remaining to extend a Boston lead to 127-123. From there, the Celtics controlled game that saw dramatic swings for both sides from the game's opening tip. Boston walks with the early advantage in a series they're heavily favored to win.

Indiana leaves with a bitter taste, having blown a golden opportunity to take a 1-0 advantage over the NBA's best team from the regular season as the No. 6 seed in the East.

This story will be updated.