Russell Westbrook has officially lost his cool.

We all know about how Westbrook and Oklahoma City Thunder players feel about playing in front of the Jazz fans at Vivint Smart Home Arena after having dust-ups in Utah last season.

Now, it appears it has reached its boiling point. As the Thunder played the Jazz for the final time during the regular season, Westbrook was recorded threatening a couple of Jazz fans during the course of the game.

"I promise you. You think I'm playing? I swear to God. I swear to God. I'll f--- you up. You and your wife. I'll f--- you up. ... I promise you. [On] everything I love -- everything I love -- I promise you," Westbrook yelled from the bench. You can view the expletive-filled incident by clicking here.

Apparently, the fan was escorted out of the game.

The rocky relationship between Westbrook and Jazz fans didn't just begin tonight. It was on display, front and center, in the NBA playoffs last year. 

After Game 6 of the Thunder's first-round playoff series loss to the Jazz, Westbrook was seen swiping at a fan's phone as he exited the court. This is what the former MVP had to say after that playoff game about Utah's fans, via USA Today's AJ Neuharth-Keusch.

"I don't confront fans, fans confront me," Westbrook said after the game. "Here in Utah, man, a lot of disrespectful, vulgar things are said to the players here with these fans. It's truly disrespectful. (They) talk about your families, your kids. It's just a disrespect to the game and I think it's something that needs to be brought up.

"I'm tired of just going out and playing and letting fans say what the hell they want to say. I'm not with that. If I was on the street, they wouldn't just come up to me and say anything crazy, because I don't play that (expletive)."

Following the game, the Jazz issued an official statement on the matter promising that they would continue to investigate the incident.

We are continuing to investigate the unfortunate exchange at tonight's game between Russell Westbrook and fans. Multiple warning cards were issued by arena security. Players and fans have a shared responsibility to create a safe and respectful environment. If it is determined that any fans violated the NBA Code of Conduct, appropriate action will be taken.

It would appear time has not healed all wounds, as there is still an extreme disdain between Westbrook and the fans of the Jazz.