Tkachuk, who will take the place of Elias Lindholm, hasn't scored a goal in 11 games. Gaudreau has no goals and five assists in his past nine games after putting up 22 points (10 goals, 12 assists) in his previous 11 games, and Monahan has five points (two goals, three assists) in his past nine games.
The Flames, who lead the San Jose Sharks by one point for first place in the Pacific Division and the Western Conference, have won back-to-back games after a four-game losing streak.
The Islanders, who are 5-1-0 in their past six games and 11-2-2 in their past 15, are three points up on the Washington Capitals for first in the Metropolitan Division entering the opener of a three-game trip through Western Canada.