Chara, the 42-year-old Bruins captain, will play after missing a 7-3 win against the Washington Capitals on Monday because of a scheduled follow-up procedure for a broken jaw sustained during the Stanley Cup Final.
Krug, placed on injured reserve on Friday, is expected to be out until at least Tuesday after sustaining an upper-body injury against the Capitals. McAvoy, who sustained an undisclosed injury against Washington, did not travel to Buffalo but is expected to skate Saturday, coach Bruce Cassidy said.
The Atlantic Division-leading Bruins are 2-4-4 in their past 10 games following an eight-game winning streak.
The Sabres have won five straight at home, outscoring opponents 25-12, and are 1-3-1 in their past five games overall after a three-game winning streak.