The Toronto Maple Leafs will be thin on the back end for Friday's game against the Buffalo Sabres.
Defenceman Morgan Rielly will not play, head coach Craig Berube confirmed. Rielly could possibly play on Saturday, Berube added.
"He's dealing with something ... I don't know yet for tomorrow (whether Rielly plays)," Berube said on Thursday, per Terry Koshan of Postmedia.
Rielly, 31, has enjoyed a strong start to the season with two goals and four assists through seven games.
The Maple Leafs will also be without Chris Tanev after the defenceman was placed on injured reserve with an upper-body injury on Thursday.
In other Leafs news, rookie Easton Cowan will make his return to the lineup after being scratched for Tuesday's game against the New Jersey Devils.
"He needs a reset, get a game to watch. It's always good for young guys to watch a game at some point. But Cowan's in a good spot," Berube said on Tuesday.
Skating mostly on the top line with Auston Matthews and Matthew Knies, Cowan has one point -- an assist -- over four games while firing five shots on net and averaging 13:11 in ice time.
To make room in the forward group, Nick Robertson will be a healthy scratch for the first time this season.
Robertson, 24, has one assist in seven games this season.
The Maple Leafs play a home-and-home set against the Sabres on Friday and Saturday, with the latter back in Toronto.
Watch Friday's game on Sportsnet ONE and Sportsnet+ beginning at 7 p.m. ET / 4 p.m. PT.