Kieran Dowell arrived on loan at Birmingham from Rangers in January
Birmingham moved 14 points clear at the top of League One after beating spirited Stevenage at St Andrew's @ Knighthead Park.
Kieran Dowell's 27th-minute penalty – his second in as many games – and Paik Seung-ho extended Birmingham's unbeaten home league record to 19 games.
But it was not all one-way traffic for the runaway leaders and Jamie Reid's fierce drive was tipped behind by goalkeeper Ryan Allsop, who then held Daniel Phillips' deflected effort.
Blues responded and Dowell headed wide and curled over.
Dowell slotted home from the spot after Louis Thompson pushed Alfons Sampsted following Jay Stansfield's pass.
Paik's low drive from just inside the box made it 2-0 in the 46th minute.
Stevenage failed to clear Alex Cochrane's corner and half-time substitute Alfie May laid the ball back to the South Korea international.
Brandon Hanlan twice fired off target and Dan Kemp's shot was deflected wide for Stevenage, while May lobbed over for Blues.
Substitute Jake Young's cushioned angled volley halved the deficit four minutes into added time after Birmingham failed to clear Dan Butler's free-kick.
Report supplied by PA Media.
Birmingham boss Chris Davies on win over Stevenage
"The two goals we conceded are really disappointing and the penalty is soft" - Stevenage boss Alex Revell
