Haliburton, who had 14 points and 10 rebounds, gave the Pacers their only lead of the game on a dramatic 21-foot jump shot to deliver a shocker after Indiana had trailed by 15 points with 9:42 remaining.

"I'm confident in my ability and feel like if I can get to my spot I'm really comfortable from there. I really had confidence in my shot," Haliburton said of the game winner.

"We're just a really resilient group. We did a great job of just walking them down. When it gets to 15, you can panic or you can talk about how do you get it to 10, to five and from there. We just stuck with it.

"We got a big stop there and they had a lot of confidence in me to make that shot."

With a game-closing 14-2 run, the Pacers seized a 1-0 lead in the best-of-seven series with game two on Sunday at Oklahoma City.

"We've got to learn from it. There are obviously a lot of things we can clean up. Credit them. They went and got that game," Thunder coach Mark Daigneault said.

"They've had so many games like that that have seemed improbable and they just play with a great spirit and keep coming."

It was the fifth 15-point-or-greater winning comeback by Indiana in this year's playoffs, the most by any team since 1998.

"They went up 15 and we just said let's just keep chipping away at the rock," Pacers coach Rick Carlisle said. "We had a lot of experience in these kind of games and our guys have a real good feel for what it's all about, giving ourselves a chance.

"We got fortunate, but made plays."

Pascal Siakam led the Pacers with 19 points while reserve Obi Toppin added 17, Myles Turner had 15 and Haliburton and Andrew Nembhard each added 14.

"It was a total team effort," said Haliburton. "We had so many guys chip in."

The finish evoked memories of the first game in the Eastern Conference finals, when a Haliburton buzzer shot forced over-time as the Pacers stunned New York. He has four such deciders in the playoffs.

The Pacers seek the first NBA crown in their 58-year history while the Thunder, a champion in 1979 as Seattle, have not won a crown since moving to Oklahoma City in 2008.

"We know we have a lot of work to do," Indiana's Carlisle said. "We have to play a lot better... and they are a menace defensively."

Indiana overcame 24 turnovers, allowing the Thunder only 11 points off them, and a 38-point performance by NBA Most Valuable Player Shai Gilgeous-Alexander.

"It's not rocket science. We have to be better," Gilgeous-Alexander said.

A 12-2 run pulled Indiana within 98-94 with 6:16 remaining in the fourth quarter, with Turner and Toppin each making two three-pointers.

The Thunder, with the NBA's best regular-season record, clung to the lead but could not hold on.

Aaron Nesmith and Nembhard sank back-to-back three-pointers to lift Indiana within 108-105 with 1:59 remaining and after a layup by Gilgeous-Alexander, Nembhard made two free throws and Siakam scored off a rebound to lift the Pacers within 110-109.

- Resilient Pacers -

Nesmith rebounded a Gilgeous-Alexander miss to set up Haliburton's game-winning shot.

"We just had to figure out how to win in so many different ways all year," Haliburton said. "We're a resilient group... we keep believing and we stay together."

The Thunder, who had a season-low 13 assists, took a 29-20 lead after one quarter and surged to a 57-45 half-time lead.

"We just had to hang in," Carlisle said. "We were within reach of still being in the game."

A Jalen Williams slam dunk produced the Thunder's biggest lead at 94-79 with 9:42 remaining, setting up the intense finish.

"As much as we can, we have to treat it like every other game," said Gilgeous-Alexander. "We haven't been in this situation but it doesn't mean our character has to change."