Luka Dončić has never exactly been a candidate for the All-Defensive teams, but his work on defense Thursday represented a low point for one of the best young players in the NBA, despite another brilliant game on offense.

The situation: a tie game with 10 seconds left between the Dallas Mavericks and Utah Jazz. Klay Thompson had just tied the game via a 3-pointer with 27 seconds remaining and the ball was in Jordan Clarkson’s hands at the top of the arc.

Dončić was tasked with guarding Jazz forward John Collins. He set up between Collins and the ball and waited. And waited. And — well, let’s just see what happened.

Dončić, focused for some reason on the already-guarded Collin Sexton, and let Collins slip past him for the most open crunch-time dunk you may ever see.

To be fair, it wasn’t teach tape for the rest of the Mavericks defense either. Big man Dereck Lively II was standing on the other side of the paint, but might have been able to stop Collins had he helped earlier. At the very least, he might have made Collins have to make another pass. Naji Marshall also could have done a better job of covering Marshall’s pass.

The basket is still on Dončić. Modern NBA defense is far, far more complicated than most fans realize, but the goal boils down to preventing a ballhandler from making the face Clarkson did when he saw Dončić really wasn’t following Collins.

There could have been some measure of redemption for Dončić on the next play, when he got the ball to an open Grimes in the corner, but Marshall, a career .307 3-point shooter, missed the would-be game-winner.

Dončić took the blame for the defensive miscue while speaking with reporters after the game:

Mavericks head coach Jason Kidd also blamed a miscommunication for the play:

It’s unfair to paint Dončić as the reason the Mavericks lost, though. He might have had a defensive lapse, but he also had 37 points on 13-of-25 shooting with nine assists and seven rebounds. His career has been built on his offensive brilliance outweighing his lack of defense and it’s arguable that’s what happened Thursday.

And yet, that play also underscores what makes Dončić so frustrating. Collins didn’t score because he was faster than Dončić, or more skilled. He scored because Dončić lost track of his man with the game on the line and thought someone, Quentin Grimes, was going to bail him out despite being in an even worse position.

The loss knocks the Mavericks down to 5-7 on the season, which isn’t how you want to follow up an NBA Finals berth.