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:
. MIDDLESBROUGH, ENGLAND - JANUARY 16: Ivan Sanchez of Birmingham City is challenged by Marvin Johnson of Middlesborough and Marc Bola of Middlesborough during the Sky Bet Championship match between Middlesbrough and Birmingham City at Riverside Stadium on January 16, 2021 in Middlesbrough, England. Sporting stadiums around the UK remain under strict restrictions due to the Coronavirus Pandemic as Government social distancing laws prohibit fans inside venues resulting in games being played behind closed doors. (Photo by Stu Forster/Getty Images)
Ivan Sanchez of Birmingham City is challenged by Marvin Johnson of Middlesbrough and Marc Bola. Photo: Stu Forster
. Marcus Bettinelli - 6
Made a few comfortable saves and collected a few crosses. Was left exposed for the goal. 6 Photo: Alex Pantling
. 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
. 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
. Dael Fry - 6
Won a few headers in the second half as Birmingham continued to pose a threat. 6 Photo: PA
. Marc Bola - 5
Made a couple of runs forward but had his hands full defensively at times. 5 Photo: Clive Brunskill
. Sam Morsy - 5
Unfortunate not to equalise with a first-half header which hit the bar and post. Spent most of the first half chasing the ball as Birmingham controlled the midfield area. Replaced at half-time. 5 Photo: Alex Pantling
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