Birmingham have decided not to appeal the red card shown to Nikola Zigic during Saturday's 1-0 defeat to Huddersfield.
The striker was sent off by match referee Andy D'Urso for a challenge on Terriers full-back Callum Woods after coming on as a half-time substitute.
City have reviewed the incident and despite feeling the Serb was harshly treated, they have opted not to appeal.
He will now miss their next three Championship fixtures against Leicester, Millwall and Leeds.
"At the time, from the other side of the pitch, I thought it was harsh," Birmingham boss Lee Clark told the club's official website.
"I have seen it since and he's genuinely gone for the ball. He's slid in, seen the lad coming, and has actually tried to pull his leg away when he was sliding, which is very difficult.
"He has caught him, but it wasn't malicious, it was a genuine attempt and I think it was a yellow card probably, not a red."