Jalen Williams erupted for 40 points as the Oklahoma City Thunder held off the Indiana Pacers to score a 120-109 victory and move to within one win of clinching the National Basketball Association (NBA) Finals on Tuesday (Manila time).

An enthralling Game 5 battle in Oklahoma saw the Pacers climb out of an 18-point first-half hole to get within two points of the Thunder in the fourth quarter.

But just as Indiana threatened the latest in a series of trademark comebacks, the Thunder found an extra gear with Williams and NBA Most Valuable Player Shai Gilgeous-Alexander steering the team to a pivotal victory.

The win leaves the Thunder 3-2 up in the best-of-seven series, meaning they can seal the NBA crown with victory in Game 6 in Indianapolis on Friday.

Williams finished with 40 points, six rebounds and four assists while Gilgeous-Alexander co-starred with 31 points and 10 assists, four blocks and two steals.

“My team-mates instill a lot of confidence in me to go out and be me,” Williams said.

“And (coach) Mark (Daigneault) has done a good job of telling me to just be myself.”

“I don’t get to be anything more and that’s given me a lot of confidence.”

Williams said Oklahoma City’s experience in Game 1 — when it blew a 15-point fourth-quarter lead to lose — had helped them close out victory.

“Tonight was the exact same game as Game 1, to be honest,” Williams said.

“Learning through these finals is what makes this team good and we were able to do that.”

Pascal Siakam led the Indiana charge with 28 points but the Pacers were left sweating on the health of star point guard Tyrese Haliburton after the loss.

Haliburton, whose fitness has been under a cloud since Game 2 of the series, left the game in the first quarter with a right calf problem before returning later in the contest.

The Pacers talisman finished with just four points from a bitterly disappointing outing — all of them coming from free throws — as the Thunder’s vaunted defense clamped down on the Pacers.

“He’s not 100 percent, it’s pretty clear,” Pacers head coach Rick Carlisle said.

“But I don’t think he’s going to miss the next game.”

“We were concerned at half time and he insisted on playing... but he’s not 100 percent. There’s a lot of guys in the series that aren’t.”

Oklahoma asserted control early in the first quarter, stretching into a 29-17 lead after Cason Wallace drained his first three-pointer of the playoffs.