Houston got 25 points from Chandler Parsons, while Omer Asik had 13 points and 13 rebounds.
The Rockets opened the third quarter with a barrage of 3-pointers. Francisco Garcia sank one to start the period and Parsons hit three more to help the Rockets build a 68-62 lead with about 7 1/2 minutes left in the quarter.
The Rockets pushed the lead to 10 points a couple of minutes later before Jackson scored five quick points to get Oklahoma City within 72-67.
That was the beginning of a 10-2 spurt for the Thunder that helped them tie it at 74-all on a putback by Durant with about three minutes remaining in the quarter. Oklahoma City led 78-77 entering the fourth quarter.
Oklahoma City limited Houston to 23 points in the third on Friday after allowing the Rockets to score 38 and 37 points, respectively, in the third quarters of the last two games.
Martin, who joined the Thunder in the trade for Harden, rebounded from a tough Game 5. He missed his first nine shots on Wednesday and finished with three points. Things were much different on Friday, when he had 21 points by halftime.
Houston was playing without key reserve Carlos Delfino, who has a bone fracture in his right foot that will require surgery.
Jeremy Lin didn't start, but played for the first time since Game 3 when he entered the game with about 2 1/2 minutes left in the first quarter. He had missed the last two games with a bruised chest muscle. He finished with three points.
Houston led by five points late in the first quarter before Oklahoma City used a 12-2 run to take a 36-31 lead about nine minutes before halftime. Fisher and Martin made consecutive 3s to cap that run.
Martin made a pair of free throws to finish his big first half before Harden swished a 3-pointer to cut Oklahoma City's lead to 58-54 at halftime.
Things got testy early, with Garcia and Kendrick Perkins pushing each other after a foul by Garcia and each getting technical fouls with about nine minutes left in the first quarter.
Garcia cooled off pretty quickly, but Perkins had to be pulled away by teammates. After things settled down, Perkins inexplicably dropped to the court and did several pushups.
Another scuffle just before halftime resulted in technicals on both Asik and Durant.
NOTES: It was a sold-out crowd of 18,357. ... Parsons scored more than 25 points for his second straight game. ... Martin came within one point of his career high in the playoffs of 26.