Pavel Buchnevich and Robert Thomas will not play for the Blues against the Blackhawks on Thursday (8:30 p.m. ET; NBCSCH, BSMW, ESPN+, SN NOW).
Each forward is out with an upper-body injury.
"Thomas has been dealing with something, so they both will not be players tomorrow," St. Louis coach Craig Berube said Wednesday. "Thomas maybe (could return Saturday). That's all I know."
Buchnevich had a goal and an assist in 19:10 of ice time in a 6-5 overtime win against the Vancouver Canucks on Tuesday. Thomas had a goal in 15:53 of ice time.
Buchnevich is second on the Blues with 66 points (25 goals, 41 assists) in 59 games this season; Thomas is third with 63 points (17 goals, 46 assists) in 70 games.
Kasperi Kapanen will shift from wing to center against the Blackhawks.
"It's new for him. We'll see how he does," Berube said. "He hasn't really (played center), probably when he was young, but he's got a good head. He's pretty solid defensively, and I feel like he's the best guy to do the job."-- Lou Korac