NBA playoffs: Jaylen Brown's clutch 3 stuns Indiana 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. The game then went into overtime, where the Celtics prevailed, 133-128, 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 10 seconds left in regulation. But they committed a turnover on a sloppy inbounds pass to breathe 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 read 5.7 seconds to secure the extra session.

There, Jayson Tatum scored 10 points, including a 3-pointer with 42.8 seconds remaining to extend a Boston lead to 127-123. From there, the Celtics controlled the game that saw dramatic swings for both sides from the opening tip. Boston walks away with the early advantage in a series it's heavily favored to win.

Turnovers, including late giveaway, doom Pacers

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. On a night where they shot 53.5% from the field and 37.1% from 3, the late turnover that set up Brown's 3-point heroics was the Pacers' defining play of the night.

Indiana had possession of the ball in the backcourt on an inbounds play with 10 seconds remaining. Andrew Nembhard was the inbounds man and first looked to Tyrese Haliburton on the baseline. With Jrue Holiday smothering Haliburton, Nembhard then looked to a cutting Siakam. But Brown was in close pursuit and made a play on the soft pass from Nembhard. The ball bounced off Siakam's hands out of bounds to set up Brown's game-tying 3-pointer.

The turnover was one of 21 for Indiana on a night where its offense was otherwise stellar. But the giveaways ultimately cost the Pacers the game. They turned the ball over three more times in overtime, including twice in the final 1:02.

Haliburton's heroics not enough

The game got off to an ominous start for the Pacers, who found themselves in a 12-0 hole less than three minutes into the first quarter. But Indiana's league-best offense bounced back to tie the game at 64 at halftime thanks in part to a logo 3 from Haliburton in the final seconds of the second quarter.

The clutch 3-pointer was one of several from Haliburton, who shot 6 of 14 from long distance while tallying 25 points, 10 assists and three steals. He hit another early in the third quarter to give Indiana a 69-64 advantage.

But the Celtics hit back with a 13-0 run later in the quarter to take an 87-75 lead. The Pacers committed three turnovers during the Boston run. But they didn't wilt.

They responded with an 18-7 run of their own capped by another Haliburton 3-pointer at the third-quarter buzzer to cut Boston's lead to 94-93.

The fourth quarter was then taut throughout before the fateful final seconds ultimately secured the extra session. Haliburton responded with another 3-pointer to start the overtime scoring, but Boston ultimately prevailed after taking the lead for good on a Tatum free throw at 124-123 with 1:12 remaining.

Boston's stars step up

The Celtics matched the Pacers' offense with big performances from across the starting lineup. Tatum tallied a game-high 36 points, including his 10 in overtime, alongside 12 rebounds, four assists and three steals. Jrue Holiday scored a season-high 28 points alongside eight assists, seven rebounds and three steals.

Brown hit just one of his four 3-pointers on the night. But it was a big one. And he was otherwise on point while tallying 26 points, seven rebounds, five assists and three steals. The Celtics shot 46.5% from the field and 33.3% from 3-point distance and secured a significant advantage at the free-throw line. Boston shot 24 of 30 from the stripe, while Indiana hit nine shots on just 10 free-throw attempts.

For Indiana, Siakam posted 24 points, 12 rebounds and seven assists. Myles Turner tallied 23 points, 10 rebounds and four assists while shooting 9 of 13 from the field and 3 of 4 from 3-point distance. Every Pacers starter but Nembhard (1) turned the ball over at least twice. Aaron Nesmith committed five turnovers while Turner posted four.

The Celtics secured the win without starting forward Kristaps Porzingis, who's been sidelined with a calf injury since Boston's first-round series against the Miami Heat. He could reportedly be ready to return by Game 4 against the Pacers.