Just for a moment, you really did wonder.
Sunderland had gone behind at home but in most uncharacteristic fashion, bounced straight back to level.
Adam Matthews went on a fine run down the flank, winning a corner and lifting the mood to fever pitch.
Sunderland were having a go, playing well, attacking aggressively and the crowd were responding to it.
Then came the crushing reality check, the hosts just incapable of defending their own box. As they have all been all season, they were vulnerable to balls into the box from wide areas, no commanding presence in the goal or in front.
A 3-1 defeat that leaves them staring down the barrel.
It was an open and even first half, Sunderland committing noticeably more bodies forward in attack.
That forced some promising openings but also left an obvious vulnerability on the counter. It was Sheffield Wednesday who fired on goal first, Adam Reach cutting inside but shooting straight at Lee Camp.
Sunderland showed plenty of positive intent, Donald Love striking from the edge of the area and just missing. Moments later Lynden Gooch drove into the box and crossed to the back post, just out the reach of Sunderland's attackers.
The home support responded with vociferous backing, the Black Cats continuing to press with intent.
The Owls looked uncertain at times, with Lucas Joao in particular wasting a number of excellent openings by holding onto the ball for too long. They always posed a threat nevertheless, with Reach again getting free in the box just after the half hour mark, blazing over with Marc Wilson bearing down.
Aiden McGeady tested Joe Wildsmith with a floated free-kick as half-time approached, but the teams went into the break level.
Sunderland started the second half on the front foot, almost going ahead when Bryan Oviedo's cross was turned into the side netting by Jack Hunt.
The game was finely poised, and with half an hour to go two quick goals raised the Stadium of Light atmosphere to a crescendo.
Wednesday's opener looked to be a fatal blow, Lee Camp's poor clearance putting his defence under pressure. The visitors quickly worked it to the far side, where a cross was floated to the back post. Atdhe Nuhiu towered over Oviedo, knocking the ball down for Joao to fire home.
If the opening goal has often caused Sunderland to crumble at home this season, it was not so on this occasion.
In the blink of an eye they were level, Gooch standing a fine ball up to the back post where George Honeyman nodded in.
The Black Cats looked set for a grandstand finish, but their set-piece gremlins returned at the worst possible moment. A wicked free-kick from Joey Pelupessy flashed across goal, where the unmarked Tom Lees converted. Lee Cattermole struck the post from range moments later and Lynden Gooch wanted a penalty when he was brought down by Barry Bannan, but the hosts had a mountain to climb.
Before long, they were down and out.
Another goal gifted away, a cross not deal with from the left. Camp denied Joao's initial effort but Nuhiu was free to nod over line.
The hosts pushed in search of an unlikely comeback but they fell short.
Birmingham now have the chance to extinguish this revival before it ever really got going.
Sunderland XI: Camp; Love, O'Shea, Wilson, Oviedo (Matthews, 63); Cattermole, McNair, Honeyman (Ejaria, 83); McGeady, Gooch (Asoro, 83), Fletcher
Subs: Steele, LuaLua, McManaman, Maja
Sheffield Wednesday XI: Wildsmith; Hunt, Lees, Venancio, Fox (Thorniley, 8); Pelupessy, Bannan (Jones, 83), Boyd, Reach; Nuhiu, Joao (Forestieri, 90)
Subs: Dawson, Rhodes, Butterfield, Matias
Bookings: Bannan, 40 McGeady, 49