The Oklahoma City Thunder, fueled by an efficient 34 points from Shai Gilgeous-Alexander, thumped the Indiana Pacers 123-107 on Sunday, punching back hard to level the NBA Finals at one game apiece.

NBA Most Valuable Player Gilgeous-Alexander connected on 11 of 21 shots and added five rebounds, eight assists and four of Oklahoma City's 10 steals as the Thunder bounced back from an agonizing game one defeat on their home floor.

Jalen Williams added 19 points, and center Chet Holmgren bounced back from a lackluster six-point game one to score 15 points with six rebounds for the Thunder, who limited Pacers star Tyrese Haliburton to 17 points, three rebounds and six assists with five turnovers.

Haliburton, who drilled the last-gasp game-winner for Indiana in their 111-110 series opening triumph, had just five points through the first three quarters.

Despite his 12 points in the fourth, the Pacers never looked like mounting the kind of comeback that saw them erase a 15-point fourth quarter deficit in game one.

"We know with them (defense) is where it starts," Gilgeous-Alexander said. "They're a high powered offense, they play fast, score a bunch of points and if you don't get stops you end up running all game and they can beat you that way."

With their latest bounce-back performance, the Thunder denied the Pacers the 2-0 lead they had grabbed in their three prior series, climbing back on even terms as the best-of-seven championship showdown heads to Indianapolis for games three and four on Wednesday and Friday.

'Game of ups and downs'

"We did some good things tonight," Gilgeous-Alexander said. "We did some things bad and we've got to be able to get better, get ready for game three."

Alex Caruso scored 20 points off the bench and fellow reserve Aaron Wiggins made five three-pointers on the way to 18 for the Thunder, who closed a back-and-forth first quarter on a 9-0 run to lead 26-20.

Holmgren punctuated the period with a three-pointer and Oklahoma City only ramped up the pressure in the second.

Another 9-0 run included a three-pointer from Williams off a feed from Holmgren and a Holmgren dunk.

After Wiggins drilled a step-back three-pointer, Gilgeous-Alexander drove for a reverse layup that pushed the Thunder lead to 52-29.

The turnovers that bedevilled the Pacers in game one began to creep up again, but Indiana offered a glimpse of just how dangerous they can be as they reeled off 10 unanswered points to slice the deficit to 13 before Oklahoma pulled away again to lead 59-41 at halftime.

The Thunder took a 93-74 lead into the fourth and were up by 22 after a three-pointer from Wiggins on a possession kept alive by three offensive rebounds.

Haliburton finally started to heat up, making three straight Pacers baskets, but his driving dunk with 8:12 remaining only cut the deficit to 20.

Myles Turner added 16 points and Pascal Siakam had 15 as seven Pacers players scored in double figures, but the Thunder maintained their record of not losing back-to-back games in these playoffs.

"Basketball, it's a game of ups and downs," Gilgeous-Alexander said. "The season's full of ups and downs. The series is full of ups and downs.

"The team that can stay level headed and get better throughout the experiences is going to come out on top."Shai Gilgeous-Alexander scored 34 points as the Oklahoma City Thunder bounced back to secure a series-levelling 123-107 victory over the Indiana Pacers in game two of the NBA Finals on Sunday.

No.1 seeds Oklahoma City, who suffered an agonising last-second loss to Indiana in game one on Thursday, roared back to life with a dominant performance on their home court to square the best-of-seven series at 1-1.

NBA Most Valuable Player Gilgeous-Alexander, who finished with 38 points in game one, once again led the way for Oklahoma City, who saw five players finish in double figures. 

Alex Caruso backed Gilgeous-Alexander with 20 points from the bench, including four three-pointers, with Aaron Wiggins bagging 18 after draining five-of-eight from outside the arc.

Indiana star Tyrese Haliburton had a frustrating outing, giving up five turnovers in the face of an improved Oklahoma City defensive performance, while being restricted to 17 points.

Gilgeous-Alexander said the Thunder's resurgent defensive effort had laid the foundations for the win.

"We just know with them, that's where it starts -- they're a high-powered offense," the Canadian star said.

"They play fast, score a bunch of points and if you don't get stops, you're running all the game and they can beat you that way," added Gilgeous-Alexander.

Gilgeous-Alexander said Oklahoma City had quickly reset after the disappointment of defeat in game one.

"Basketball is a game of ups and downs, the season is full of ups and downs," he said. "The series is full of ups and downs and it's about the team that can stay level-headed and get better throughout the experiences that are going to come out on top."