However, the team were quick to respond, with Craig Berube revealing just hours later that it was an upper-body ailment, with the veteran coach describing the situation as "nothing serious".
This should allow Maple Leafs fans to breathe a massive sigh of relief, as losing Matthews for an extended period of time could completely derail their upcoming season, especially given the production he's had offensively in the past few seasons.
Two seasons ago, Matthews tallied 40 goals, and that drop off in production was due to a major wrist injury that held him back all season, so he has dealt with injury concerns over the years, but for the most part, Matthews has been very available throughout his NHL career. With the regular season just over two weeks away, the team will now need to be careful with his activities heading into the season, and if he's still 100% healthy, there's no reason to expect anything but another stellar campaign from him.