It's the day before the Toronto Maple Leafs officially start their season, and they may have to deal with another injury to a key piece of the roster.

In Tuesday's practice, Mitch Marner and Wayne Simmonds had an awkward collision that sent Marner off the ice.

According to TSN's Mark Masters on Leaf's Lunch, Marner skated over to the trainers after the collision and had a conversation with them and head coach Sheldon Keefe before leaving the ice.

The team has yet to release an official statement, but Keefe has said it is 'just precautionary' at this point and that Marner will be evaluated on Wednesday morning and the team will 'go from there.' 

The Maple Leafs are already without Auston Matthews and Ilya Mikheyev on opening night as Toronto officially starts the 2021-22 NHL season on Wednesday against the Montreal Canadiens.