Wilfried Bony came off the bench to score twice in three minutes as Swansea City came from behind to beat Birmingham and avenge their League Cup elimination.
The two sides had met at St Andrew’s in the League Cup in late September, with the Blues triumphing 3-1 to knock the holders out of that competition.
Four months on, it looked like history might repeat itself in the Midlands as Lee Novak’s header gave Lee Clark’s hosts a half-time lead.
Birmingham City 1-2 Swansea City
The FA Cup with Budweiser
Fourth Round Proper
3pm, Saturday 25 January
St Andrew's
Winners receive £90000
By Ben Pearce
However, Bony came on at half time and struck in the 67th and 69th minute to secure the Welsh club’s progress into the Fifth Round.
Swansea looked short of confidence at the start and Birmingham threatened early on as debutant Albert Rusnak – who is on loan from Manchester City – delivered a low cross that Ashley Williams forced behind.
The hosts went on to take the lead in the 14th minute as Paul Caddis delivered an inswinging cross from the right, and Novak got a flicked touch with his head to beat Gerhard Tremmel, netting his fourth goal in six FA Cup appearances.
Birmingham nearly doubled their lead moments later as Tremmel spilled the ball, but Williams denied Rusnak with a goal-line clearance.
Swansea recovered and Neil Taylor crossed for Pablo Hernandez, who blazed over – and Jordi Amat then wasted a golden opportunity, shooting over at close range following a free-kick into the box.
However, Birmingham then went close in injury-time as Tremmel tipped Hancox’s dipping 25-yard strike over the bar.
Lee Novak celebrates the opening goal.
Bony came on at the interval, but Swansea nearly shot themselves in the foot as Dwight Tiendalli played a loose pass inside his own box, forcing Williams to win a crucial challenge with Birmingham’s Shane Ferguson.
Bony then began to threaten though, being denied by a superb tackle from Hancox in the penalty area before forcing a low save from Colin Doyle at the near post.
It was third time lucky for the big Ivorian as he equalised in the 67th minute, volleying home from Roland Lamah’s cross.
Birmingham sought to hit back straight away, but they left themselves open on the counter-attack, and Lamah broke away twice in quick succession.
The first time Doyle rushed out to smother at his feet but, moments later, the winger was through again. This time he elected to pass, and Bony stepped past Doyle to finish again and turn the tie on its head.
City battled for a leveller and Clark threw on Tom Adeyemi and Peter Lovenkrands, with the latter drawing a low save from Tremmel in the closing stages, but the home side were unable to force a replay.
Birmingham City: Doyle, Caddis, Packwood, Robinson, Hancox, Lee (Lovenkrands 81), Brown, Burke, Rusnak, Ferguson (Adeyemi 74), Novak.
Manager: Lee Clark
Goals: Lee Novak (14)
Swansea: Tremmel, Tiendalli, Chico, Williams, Taylor, Britton, Amat, Pozuelo, Hernandez (Bony 45), Lamah, Vazquez (Routledge 64).
Manager: Michael Laudrup
Goals: Wilfried Bony (67, 69).
