Lukas Jutkiewicz - who else - wins another free kick.
It causes more chaos and from it Dion Sanderson is denied an equaliser by a goal-line block from Trai Hume and Blues player George Hall, before Anthony Patterson makes a good save from Sanderson's follow-up.
Sunderland survive. For now.
That triple change has worked for John Eustace and Birmingham are right back in the match.
Sunderland had been looking uncomfortable as Blues upped the pressure and now they have some work to do in these last few minutes.
For Blues, they have to get the ball in and around Jutkiewicz.