The Flames announced Friday that Sean Monahan and Kris Versteeg will miss the remainder of the season due to injury.
"Sean has been battling through two injuries over the past month and it has reached a stage where it must be addressed," said GM Brad Treliving.
The Flames top-line centre, who has a team-leading 31 goals, will undergo surgery in the coming days.
Left-winger Versteeg had recently returned to the lineup after being sidelined 48 games due to hip surgery.
Defenceman T.J. Brodie and left-winger Matthew Tkachuk did not travel with the team for their two-game road swing through California, that begins with a Saturday matinee against the San Jose Sharks.
"Brodes, both him and Chucky are still day-to-day," said coach Glen Gulutzan. "We're still hoping that at some point they can come back."
MAYFAIR DIAGNOSTICS INJURY REPORT - 23.02.18
A recap of the Flames injury situation