Kozun worked hard this preseason to crack the Leafs lineup. He collided with the end boards during a 4-1 loss to the Detroit Red Wings on Friday night. He needed to be helped off the ice, and did not return.
He was scheduled to receive an MRI on Saturday, and did not travel with his team for their home and home series.
The Leafs have lost two straight games, and notably had a second fan throw a jersey on the ice on Friday. Kozun remained positive Saturday with a tweet to fans.