Birmingham City ended Middlesbrough's three-match winning run in the Championship with two goals in three second-half minutes at the Riverside Stadium.
Boro bossed a cagey first half, and Jonny Howson went closest when his shot was pushed away by Blues goalkeeper Matija Sarkic.
But City went ahead soon after the break with their first attempt on target, Marc Roberts heading into an empty net after Boro goalkeeper Joe Lumley charged out but missed Jordan Graham's free-kick.
And Scott Hogan quickly doubled the lead, running on to a simple ball over the Boro defence before coolly slotting past Lumley to give Blues back-to-back victories.