Until Parker's game-winner, it was almost as if nothing had changed for Oklahoma City.
Tim Duncan led the Spurs with 20 points and eight rebounds. Parker also had 11 assists and hit a 3-pointer with 28.4 seconds left that tied the game at 84 and set up his buzzer-beater on the next possession.
Durant also had 14 rebounds. Russell Westbrook scored 18 points but made a poor pass on the Thunder's final possession that gave the ball back to the Spurs with 5.9 seconds left, giving Parker plenty of time to set and release his shot.
The Thunder are starting anew with newcomers Kevin Martin and Jeremy Lamb, who along with draft picks, are what the Thunder got in exchange for their third-leading scorer. Small-market Oklahoma City wasn't willing to offer Harden a maximum contract, and the No. 3 overall pick in the 2009 draft wouldn't accept its lesser offer.
By Wednesday, Harden had agreed to a five-year, $80 million extension with the Rockets. That night, he stepped into Houston's starting lineup and became the first player in NBA history to have more than 30 points and 12 assists in a debut with a new team.
Asked before Thursday's game whether the second-guessing had begun, Brooks didn't linger on the topic.
"He's played good basketball. He had a good game," Brooks said. "We're real focused on our group, our guys and moving forward."
Westbrook, who took responsibility for losing Parker on the screen on the game's final play, acknowledged the first game without Harden didn't feel the same.
"It was definitely odd not playing and practicing with him," Westbrook said. "But we still need to find a way to win."
Martin had 15 points and was Oklahoma City's only bench player in double figures. But backup Eric Maynor made his own big contribution, hitting a half-court heave to tie the game at the end of the third quarter.