Middlesbrough moved up to sixth in the Championship by coming from behind to hand Birmingham City their third straight defeat.
The Blues started well and went in front when Maxime Colin lashed home a loose ball inside the penalty area.
But the visitors scored twice in four minutes through Britt Assombalonga and George Saville to lead at the break.
Keeper Neil Etheridge fumbled a cross into his own goal and Lewis Wing's long-range effort wrapped up the win.
Birmingham almost took the lead after only three minutes when Scott Hogan headed wide, but they did not have to wait long for the opener.