Nikola Jokic's 53-point masterpiece Sunday night was somewhat overshadowed ... the Nuggets' superstar had a heated exchange with a "fan," who turned out to be Suns' owner Mat Ishbia.

Ishbia was sitting along the baseline for Game 4 of the Western Conference Semifinals game between the Nuggets and Suns ... when things got testy in the second quarter.

Suns forward Josh Okogie was trying to gain possession of a loose ball when he flew into the area where Ishbia was sitting, prompting Mat to check on his player. The owner was holding the basketball.

Jokic sprinted over to Ishbia and tried to take it from his arms, but the Suns' owner wasn't giving it up, which clearly ticked Nikola off.

As Jokic tries to get the ball back from the 43-year-old billionaire, the two-time MVP nudges him with his left forearm, prompting an exaggerated flop from Ishbia, who fell backward in his seat.

Fortunately, officials quickly intervened and were able to separate everyone ... however, Nikola was slapped with a technical foul for "deliberately" making contact with Ishbia.

Ishbia reportedly told the Associated Press at halftime that he was more concerned with the outcome of the playoff game than the incident with Jokic.

"The fan put a hand on me first," Jokic told reporters after the game. "I thought the league is supposed to protect us. But maybe I'm wrong."

Meanwhile, Nuggets head coach Mike Malone supported his star player, saying he thought it was "crazy" Jokić got a technical foul for trying to get the ball from a fan, and added he doesn't "give a s***" the fan was the Suns' owner.

The NBA has yet to announce if they will discipline Jokić further with a fine or suspension, but with Game 5 on Tuesday in Denver and the series hanging in the balance, Nuggets fans are holding their collective breaths.