A Stewart Downing own goal, Mikael Forssell's close-range strike and Gary McSheffrey's penalty gave Birmingham a 3-0 win over Middlesbrough.
Boro started brightly, with Jeremie Aliadiere firing straight at Maik Taylor and Downing shooting over the crossbar.
Downing had his head in his hands on 22 minutes, though, when he diverted McSheffrey's free-kick past Mark Schwarzer for the opening goal.
The winger tried to make amends with a long-range effort saved by Taylor, but after Forssell fired into the sidenetting, he netted on 45 when he poked in Seb Larsson's corner from close range.
After the break, a Forssell goal was ruled offside and Larsson shot wide before Boro saw Tuncay Sanli draw a fine save from Taylor with a 25-yard piledriver.
McSheffrey put the icing on the cake from the spot, after being fouled himself, in stoppage time.