After St. Louis wingers Andy McDonald and Andy Steen were hurt during practice Tuesday, the Blues announced that McDonald has been placed on injured reserve with a left knee injury.
The team listed McDonald listed as week to week and Alex Steen as day to day with an upper-body injury.
"It happens. We've got lots of guys coming in that are hungry, guys that have played in the NHL," Blues coach Ken Hitchcock said Wednesday. "So we shouldn't miss a beat."
Hitchock said Steen might be available for Thursday night's game against the Chicago Blackhawks.
McDonald has three goals and 11 points in 18 games this season. Steen has a team-leading 16 points in 18 games.