NBA star Nikola Jokic could be facing a lengthy suspension ... after he injured Markieff Morris on Monday night with a violent cheap shot.

The play all went down at the end of the fourth quarter of the Nuggets' game against the Heat ... when Jokic felt he was fouled by Morris while dribbling the ball up the court in a 111-94 game.

In video of the incident, you can see right after Morris threw his body into Jokic's -- the 6-foot-11, 284-pound center charged at Morris' back and hurled an elbow that caused the Heat player to crash to the ground.

Immediately, players and coaches got into a scrum -- and at one point, Miami star Jimmy Butler appeared to challenge somebody on the Nuggets to a fight at center court.

Eventually, everybody was separated and Jokic was ejected ... but Morris appeared to be really hurt on the play.

In fact, a stretcher was brought out for the 32-year-old, but fortunately, he was able to walk off the court.

The Heat announced Morris was dealing with a neck injury as a result of the foul -- and his status going forward is unclear.

For his part, Jokic -- whose Nuggets went on to win 113-96 -- called the play "stupid" and said he shouldn't have reacted the way he did.

NBA fine, and possibly suspension, coming for Jokic in 3 ... 2 ...