Noe Pamarot departed early with a knee injury while both Reto Ziegler and Noureddine Naybet complained of hamstring problems and had to be substituted.
"Pamarot has a bad injury to his knee," reported Head Coach Martin Jol at St Andrews. "If it's his medial ligament it will be three, four or five weeks.
"Ziegler has had problems with his hamstrings all season. He's a young lad and played maybe 140 minutes for his country last week but he's very fit and he said he was alright.
"Naybet couldn't really play in the second half but went out, although we had to change that in the end because he couldn't play on. He had a hamstring as well, the same problem as before."
We'll have an update from the medical team later today...
Saturday's draw at Birmingham came at a cost with three players suffering injuries.