Darren Bent smashed through the 20-goal barrier as Sunderland survived a second-half fightback to beat Birmingham 3-1.
The England international fired the home side into a fifth-minute lead and then added a second six minutes later to put them firmly in the driving seat.
However, Birmingham emerged after the break in a much more determined mood and having reduced the deficit through Cameron Jerome's strike on the hour they threatened to leave with a point.
Sunderland were indebted to the brilliance of goalkeeper Craig Gordon, who made fine saves from Jerome, Christian Benitez, Stephen Carr and Liam Ridgewell.
Fraizer Campbell's 88th-minute strike ended the hopes of Alex McLeish's men.
The Black Cats had been threatening to throw away all their good work from before the break in front of an increasingly anxious crowd of 37,962.
But ultimately, they did enough to secure another three-point haul and have now lost just one of their last eight league games.
Defeat for Birmingham was a reverse of the result when the two sides met at St Andrew's in October and dented their hopes of closing the gap on arch-rivals Aston Villa in the top half of the table.
The game was Sunderland's fourth in succession at the Stadium of Light, and with the previous three having yielded five points, manager Steve Bruce was keen to increase that tally to eight ahead of tough away trips to Aston Villa and Liverpool.
By the time the game was just 11 minutes old, his team were on target to do just that, thanks largely to Bent's continued potency.
The #10million man's 19 goals before kick-off represented a major contribution to the 31 points the Wearsiders had collected from their first 29 games of the campaign.
However, a lightning quick double took him past the 20-goal mark, the accepted line which separates the top strikers from the rest, and put the home side firmly in control.
His first came after just five minutes when Benjani Mwaruwari, making his first start for the club in place of the injured Kenwyne Jones, saw his effort blocked and Bent rattled home the rebound from close range.
The second six minutes later was all his own work as he ran on to Steed Malbranque's fine pass and cut inside defender Scott Dann before rifling a low drive past the helpless Hart.
It could have been 3-0 with 15 minutes gone but for Hart's save from Campbell, and it was then that Birmingham belatedly launched their fightback.
Twice inside a minute, Gordon had to dive full-length to turn away Keith Fahey strikes, and the Scot just managed to get enough on Benitez's 30th-minute header to tip it against the crossbar.
But the home side finished the half once again in the ascendancy, with Malbranque blazing over after Hart had palmed away Kieran Richardson's curling shot and then firing just wide from distance.
In a scrappy start to the second half, City were making a fist of it once again, although without making much of an impression going forward.
There was warm applause and even a song for former Sunderland hero Kevin Phillips as he warmed up on the sidelines, but it was Jerome who should have breathed new life into Birmingham's efforts to drag themselves back into the game with 54 minutes gone.
He ran in behind defender John Mensah, who had earlier required treatment for a knee injury, and went one-one-one with Gordon, but the goalkeeper came out on top as he blocked with his legs.
Gordon excelled himself once again with a fine 59th-minute double save from Benitez and Carr, but he was finally beaten on the hour as his defence deserted him.
Jerome got in down the right and powered his way into the box before chipping a shot over the helpless Scot.
Birmingham would have been level 11 minutes later had Gordon not managed to claw away Ridgewell's goal-bound looping header, and fellow defender Roger Johnson headed wastefully over from the resulting corner.
There was a collective sharp intake of breath when Phillips, a 59th-minute replacement for Benitez, looped a header onto the roof of the net with nine minutes remaining.
Bent might have calmed the nerves when he went through with 86 minutes gone and lifted the ball over the advancing Hart, but his effort lacked pace and Johnson was able to get back to clear.
However, Campbell sealed the win when he met substitute Jordan Henderson's cross to finally kill off the visitors.
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