Toronto Maple Leafs prospect William Nylander is still feeling the effects of a concussion he suffered at the world junior hockey championship on Dec. 26.

Nylander, who was the top star on a highly-touted Swedish team, was hit by Switzerland’s Chris Egli in his team’s opening game of the tournament and hasn’t played since.

According to Sportsnet’s Damien Cox, Nylander is back in North America starting his return-to-play protocol with the Toronto Marlies of the AHL. It’s unclear how long Nylander will be sidelined but Cox speculated he could miss more than a month.

Prior to leaving for the world juniors, Nylander led the AHL in scoring with 14 goals, 20 assists in 27 games.

Kyle Dubas, the Marlies general manager and Maple Leafs assistant GM, recently told Dean Blundell & Co. on Sportsnet 590 The Fan that the organization won’t rush Nylander back.

“The process now for William is for us to be very cautious and make sure that he’s returning when he’s absolutely one hundred per cent, no questions asked,” Dubas said. “We’ll get him back, our doctors will take over the process and we’ll look forward to getting him back into the Marlies lineup, but only when he’s one hundred per cent cleared and ready to go by our doctors.”