It is unlikely Sunderland boss Steve Bruce, returning to St Andrew's for the first time since his exit in 2007, would have reciprocated Yeung's affections but he will at least have been heartened by the warm applause from both sets of fans.
However, Bruce's smiles quickly changed to scowls as his players struggled to contend with their hosts, who made a lively start despite going into the game on the back of four defeats in a row.
After defender Roger Johnson headed harmlessly over the bar on 20 minutes, the blue tide began to roll forward with McFadden, Jerome and Christian Benitez all making a nuisance of themselves.
Ecuador striker Benitez broke dangerously on the left and crossed to McFadden on the six yard line, who was denied by the sliding legs of Kieran Richardson.
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Moments later Benitez turned inside the box and shot straight at Craig Gordon's out-stretched palm, but it wasn't long before the keeper was picking the ball out of the net and his sleepy defenders were totally to blame.
Dead ball specialist Larsson curled in a low free-kick from 25 yards and as the ball bounced unchallenged into the box, it flicked off Ridgewell's body and into the net.
Three minutes into the second period the roar from the Blues fans got even louder with a magnificent strike from McFadden.
Larsson chipped in for Jerome, lurking on the edge of the box, and he flicked the ball on to McFadden.
The Scot still had plenty of work to do but he expertly turned inside Phil Bardsley and coolly slotted the ball past the wrong-footed Gordon.
With 20 minutes remaining Sunderland boss Bruce sent on the cavalry, with three midfielders making way for substitutes George McCartney, Fraizer Campbell and Dutchman Boudewijn Zenden.
How Sunderland could have done with a rogue inflatable, following Bent's deflected winner off a beach ball against Liverpool last week, and once again they got a lucky break.
After 82 minutes in which they had been completely bereft of ideas and willingness, they found themselves right back in it thanks to the boot of one of their opponents.
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Andy Reid sent in a free-kick from the right and with Michael Turner's header looping goal-bound over the flapping Joe Hart, Dann stretched out his leg and planted the ball into his own net.
For the first time in the game Birmingham were wobbling and when Reid sent over a cross, Bent side-footed the ball agonisingly just wide of the post.
The Blues were now desperately hanging on and substitutes Zenden and Campbell both had chances to grab an undeserved equaliser.
A second Sunderland goal would have been harsh on the hard-working and lively Birmingham players and they managed to hold on to stop the rot and pick up three vital points.
Birmingham boss Alex McLeish: "It was a big result. It was important the players didn't get anxious and up to the goal we looked excellent.
"The resilience of the new young players was terrific."
Sunderland manager Steve Bruce: "We didn't play anything near the standard we have set over the last few weeks.
"If you have six or seven players not playing well you are going to be in trouble. At least for an hour we were second best. Birmingham were the better team."
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