Birmingham City have walked away from the Riverside Stadium with all three points courtesy of a late Nikola Zigic goal.
The win sees Lee Clark's side rise to 11th in the Championship table, while Middlesbrough remain ninth.
Zigic twice put his strike partner Wes Thomas through on goal early on, but he was unable to break the deadlock.
Scott McDonald thought that he had opened the scoring 10 minutes before the break, but his goal was chalked off by the linesman.
The Australian was flagged offside as he followed in George Friend's shot, which had been palmed away by Jack Butland.
The England international was alert to deny McDonald once more after the break as the visitors again threatened to score.
As the clock ticked down, it was left to Zigic to secure the points for the Blues, as he bundled the ball over the line with just under 10 minutes left to play.
