The Toronto Maple Leafs will be without three key players when they take on the Calgary Flames on Monday.
Jake Muzzin has a broken bone in his face that will require the defenseman to miss some time.
"It could be a day-to-day situation we're not sure, we have to give it some time to settle," Maple Leafs coach Sheldon Keefe said. "When he comes back, it'll have to be with a full face shield."
Muzzin has a goal and 11 assists and has dressed for all 19 games this season. His presence helped stabilize the middle defensive pair alongside the improved play of Justin Holl.
Travis Dermott will move up to play with Holl on the middle defense pair on Monday.
"It's a great opportunity and something he's been waiting for and something we've been preparing him for," Keefe said of Dermott. "That's a lot of the approach we've taken with Derms here is to get him to reset and prepare for a greater role."
Dermott has one goal in 15 games this season. He skated with veteran Zach Bogosian for 14 of those games.
Mikko Lehtonen was Dermott's defensive partner on Thursday against the Ottawa Senators.
Lehtonen draws into the lineup and will skate with Bogosian.
The 26-year-old Finnish defenseman has three assists in seven games this season.
Zach Hyman is day-to-day with an undisclosed injury. He missed Thursday's game against the Senators after blocking a shot off his foot. He returned on Saturday but took another blocked shot off the same foot in the second period. After briefly leaving to the locker room for evaluation, Hyman returned and finished the game.
Hyman has four goals and six assists in 18 games this season.
Joe Thornton's injury was not disclosed. Keefe told reporters that he expected Thornton to be a game-time decision but learned he would be unavailable minutes before speaking to reporters.
Earlier this season, Thornton missed 10 games with a rib fracture before returning the lineup last week against the Senators.
Thornton has three goals and six assists in nine games.