Blues Head Coach Craig Berube said Bortuzzo needed a maintenance day and whether he would play Thursday would be a gametime decision.
Carl Gunnarsson skated in Bortuzzo's spot alongside Joel Edmundson in practice, so if Bortuzzo doesn't play, it's possible Gunnarsson would be in the lineup for the first time in this series.
Judging by the morning skate, it looks like Berube will keep the rest of the lineup the same for Game 5 (7:30 p.m., FSMW, KMOX).
"We've shown we've had success with those lines, so there's no point to change anything," Blues forward David Perron said. "Coaches always have backup plans depending on the situation in a game or moving forward, but (changing lines is) not something we come into the room and expect... You can look at the positives. (Berube) is trusting the guys that have done the job and and we've got to do it again tonight."