Westbrook's dunk tied the game at 90-90 with four seconds remaining. Memphis failed to score on the ensuing possession after it was determined Zach Randolph's layup was attempted after the buzzer.
The overtime marked the fourth consecutive OT game for the Thunder-Grizzlies series.
The Grizzlies held on in the extra period to win 100-99 and take a 3-2 series lead on the Thunder. This story will be updated.