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 123-107 performance on their home court.
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."