Going into Monday afternoon's game with a three-game losing run behind him and a very public demand of promotion from outspoken owner Ken Bates hanging over his head, some could have been forgiven for writing Simon Grayson's Elland Road obituary when his men fell behind to Charlie Austin's 69th-minute opener.
But the under-pressure boss was given a leg-up by Brian Easton's own goal with two minutes left and, when it looked as though he would have to take a draw against 10 men back to his chairman, McCormack pounced on Lee Grant's fumble of Andros Townsend's long-range strike to send his manager on an emotional charge of celebration down the touchline.
The end result was perhaps harsh on Burnley, who had looked set to record an eighth win in nine games when Austin scored - his goal coming some 40 minutes after Kieran Trippier had been sent off for two bookings, both of which came for fouls on lively debutant Townsend.
But it was Leeds who had the last word, with top scorer McCormack coming off the bench to grab his 12th and most important of the season.
Grayson said after Saturday's 4-1 loss to Barnsley that some players may never play for him again and he stayed true to his word, making five changes, although it was Burnley who started better with Austin spurning a one-on-one chance.
Leeds then lost captain Patrick Kisnorbo to a 14th-minute knee injury that forced Grayson into another reshuffle, and he was thankful to see Andy Lonergan turn Austin's opportunistic 25-yard drive over as he changed his side around.
Burnley began to fade after that second Austin effort and Townsend in particular opted to try and swing momentum in favour of the home side. Tripper was the man in his sights and twice in the space of six minutes he torched past the full-back, with referee Mike Brown brandishing a yellow card on both occasions, with the second one perhaps only worthy of a warning.
In between the two bookings Townsend ran at the Burnley defence and drilled wide but, after that and Trippier's dismissal, both sides seemed without idea and limped through to the interval.
Leeds displayed a shade more invention at the start of the second half, with Ramon Nunez twice putting in crosses that caused Grant problems and Townsend fizzing a strike over from the corner of the area.
Townsend was relentless in his pursuit of whoever was occupying Burnley's right-back berth and, after he drew a foul and a booking from David Edgar, Leeds mounted their first real spell of pressure which saw Brian Easton head away from under his own bar and Darren O'Dea then clip the top of the goal with a looping header.
Ben Mee then received the fourth yellow card of the afternoon awarded for a foul on Townsend, and from the subsequent free-kick, Nunez worked Grant for the first time.
Leeds rookie Zac Thompson then saw a volley scrape past Grant's post from 25 yards, before Austin went one better at the other end, giving Burnley the lead out of nothing.
A long ball from Dean Marney fell to him in the box and, as the Leeds defence held back, he snapped at a half-volley on the turn and found Lonergan's bottom corner with his 10th of the season.
Leeds were initially stunned, but got a fortuitous break when Easton turned Adam Clayton's corner beyond Grant with four minutes left and then, when a draw looked on, McCormack pounced to offer his boss some welcome relief.
Townsend's 25-yarder should have been a regulation save for Grant, but the keeper shelled the ball and McCormack did the rest.