Upon returning to practice Friday, Auston Matthews shed some light on the upper-body injury that's kept him out of the Toronto Maple Leafs' last six games.

Matthews said he experienced "normal concussion symptoms" after colliding with teammate Morgan Rielly in Pittsburgh on Dec. 9, according to TSN's Kristen Shilton.

Here's the play:

Matthews shaken up after colliding with Rielly pic.twitter.com/5RB6krUF9A — Flintor (@TheFlintor) December 10, 2017

Matthews confirmed he did go through protocol, and added that he didn't start to feel concussion symptoms until after the game and into the next day. He'll be a game-time decision for Saturday's matchup with the New York Rangers, which is Toronto's final game before the Christmas break.

The 20-year-old also missed five games in November with an upper-body injury, limiting him to just 26 games this season. In those contests, however, he's recorded 26 points, good enough to lead the Leafs.