The Birmingham City striker swivelled expertly inside the box in the final minute to rifle substitute Nikola Zigic's flick-on across Lee Grant and in to the far corner.
It was a harsh, undeserving conclusion for the Clarets who battled for half-an-hour with a man less following referee Darren Drysdale's decision to dismiss midfielder Dean Marney following what was deemed to be a reckless challenge on Brum left-back Paul Robinson.
However, Sean Dyche's side failed to reach the highs of last weekend's display at Millwall. The pace, panache and power of that display at the Lions' Den had fizzled out and the opening 45 minutes was played out at a disturbingly pedestrian tempo.
The hosts often found solace down the right, with Ross Wallace and Kieran Trippier combining to cause ample problems for former Trotter Robinson. And the first opportunity arised from that very outlet with Trippier providing the pass for Wallace who cut past the City defender at the by-line and clipped a cross in to Danny Ings whose header flashed wide of the post with Jack Butland at full stretch.
Marney attempted to raise the lacklustre rhythm of the fixture with bursts through the centre of the park and it was his energy and desire that forced the next opening. The midfielder found Trippier down the right, and when the full-back's cross was cleared by former Claret Steven Caldwell, Wallace pumped the ball back in to the box where Ings cranked his neck and headed over.
But the Clarets conceded their first league goal of the year in the 21st minute. Imposing centre-back Curtis Davies, who opened the scoring in the 2-2 stalemate at St Andrews, inexplicably rose unmarked to nestle a header from Ross Hall's set-piece in to the corner.
The home side pressed for an equaliser but failed to carve a genuine opening. The closest they came in the closing stages of the first half saw Marney once again win possession before Chris McCann swapped passes with Ings only to see his deflected, looping effort caught by Butland.
Dyche made a tactical change at half-time, moving Junior Stanislas to the right, Ings to the left, and Wallace in behind Sam Vokes. And that change almost paid dividends immediately when Vokes glanced Trippier's diagonal pass in to the area and Ings beat Caldwell for pace but his right-footed effort came back off the bar with Butland well beaten.
The young England prospect then showed why he is so highly rated when his superb, fingertip save at full-stretch denied Vokes's sweeping volley from Stanislas's enticing centre.
But Brum couldn't survive the early bombardment and in the next breath the Clarets were awarded a penalty. Stanislas latched on to Vokes's header and was impeded by Robinson. Drysdale, who had a decidedly questionnable display, pointed to the spot and Wallace made no mistake, drilling the spot kick down the middle.
Davies almost restored the away side's lead with another free header from a corner, though this time Grant was equal to the attempt, but then the Clarets were reduced to 10 men in extremely controversial fashion. Both Clark and Dyche were united in their opinion of Marney's challenge in the post match press conference, stating the midfielder's tackle on Robinson was fair, but Drysdale thought differently and held the red card aloft.
But even with 10 men the Clarets dominated possession for large chunks, while City found winger Chris Burke as an outlet to relieve some of the pressure. It was Burke's precise cross that almost saw Zigic fire Brum in front, his close range header cannoning back off the post.
Grant saved a Zigic header and sub Nathan Redmond pulled an effort wide of the post from the edge of the box as the visitor's started to get on top. But their persistance was rewarded when Wembley hero Wade Elliott delicately lifted the ball in towards the penalty spot, Zigic provided the flick on, while King had the time and space to shape himself before rifling across Grant and in to the far corner.
It was a result that saw Burnley's play-off ambitions tarnished slightly, with Watford winning convincingly at Nottingham Forest, but they'll be ready to go again in seven days time when they take on Peterborough United at London Road.