Blues forward Scott Hogan scored the only goal of the game in the 26th minute as former Boro boss Aitor Karanka claimed a win over his former club.
Our Boro writer Joe Nicholson has dished out his marks from the match– scroll down and flick through the pages of our picture gallery to see how each player fared:
1. Marcus Bettinelli - 6
Made a few comfortable saves and collected a few crosses. Was left exposed for the goal. 6 Photo: Alex Pantling
2. Anfernee Dijksteel - 6
Birmingham’s best attacks came down the other flank. Tucked in when he had to and made some important interceptions. 6 Photo: Clive Brunskill
3. Paddy McNair - 6
Was involved in a scuffle with Ivan Sanchez in the first half. Played a couple of cross-field passes yet Boro found it tough to get on the front foot. 6 Photo: Alex Pantling
4. Dael Fry - 6
Won a few headers in the second half as Birmingham continued to pose a threat. 6 Photo: PA