The heated exchange came early in the second quarter of the Thunder's 98-89 victory over the Utah Jazz on Monday night.
Westbrook was on the bench and stood when he heard what the fans said. He said they told him to "get down on my knees like I used to." After that, Westbrook was seen on video cursing at the man and threatening him and his wife.
After the game, Westbrook spoke of verbal abuse he and teammates hear from spectators on the road. Much of it has been directed at their families, according to Westbrook. He said he will no longer tolerate such disrespect.
"There's got to be something done," Westbrook said. "There's got to be some consequences for those type of people that come to the game just to say and do whatever they want to say. I don't think it's fair to the players."
Westbrook recently objected to a young fan touching him on the sideline during a game.
Jazz security repeatedly warned fans in the area, and the team said after the game it will investigate what happened.
"Players and fans have a shared responsibility to create a safe and respectful environment," the team statement said. "If it is determined that any fans violated the NBA code of conduct, appropriate action will be taken."
The fan said in a TV interview neither he nor his wife cursed at Westbrook.
Westbrook's teammates came to his defense following the game. Raymond Felton, who did not play, sat near Westbrook on the bench. Felton confirmed he also heard the taunts.
"He's not coming off and talking to the fans, just saying stuff to them and just blurting out words," Felton said. "He's not. They're coming at him first. When is there going to be a point where there's going to be protecting those players? People can say whatever what they want to say us during games and yell out stuff and talk about our families and talk about our kids."
Westbrook finished with 23 points, 11 rebounds, and eight assists.
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