Ten-man Burnley refused to go down without a fight but a fifth defeat in six games leaves the Clarets needing to defy all logic to keep their promotion dream alive.
Marvin Bartley's controversial first-half dismissal for a foul on Luke Chambers left Burnley with an hour to play against their fellow drinkers in the play-offs' last-chance saloon.
Chris Eagles almost gives Burnley the lead
And the handicap ultimately proved too great as two late goals from substitute David McGoldrick were enough to give Nottingham Forest their first win in ten games.
The Clarets showed the battling qualities that have been missing from some of their recent performances as they bravely looked to upset the odds.
But with ten men making life even more difficult they again lacked a real threat in front of goal as their goalless run away from extended to three games.
Goalkeeper Brian Jensen did his best to try and secure at least a point with a heroic performance but when he was finally beaten by McGoldrick 17 minutes from time Burnley couldn't find a response.
And when McGoldrick delivered the final blow in stoppage time, the Clarets' top-six hopes faded further into the night air.
Marvin Bartley's challenge on Luke Chambers ended in red
Bartley's return to fitness and Jack Cork's all-clear following his heart scare meant further changes to the Clarets' midfield, with Danny Fox also back after suspension.
And with top scorer Jay Rodriguez missing out with a thigh injury it was another re-shuffled pack from boss Eddie Howe in a quest to rediscover the winning thread.
That meant a central striking role for Nathan Delfouneso but neither side managed an effort at goal in a cagey opening half hour.
With the classy Cork controlling things in midfield that didn't perturb the Clarets as they eased their way comfortably into the game to add the frustration growing among the Forest fans who hadn't seen their side win for nine games.
That unease would have got worse had Burnley managed to strike first and with 30 minutes gone they were only a toe-end from going in front.
Delfouneso's shot was blocked by Wes Morgan but when the ball looped up off the big defender's back, Chris Eagles pounced to let fly with a low drive which goalkeeper Lee Camp somehow managed to deflect over the bar with his outstretched boot.
The Clarets were looking to build on that momentum when disaster struck just two minutes later as Bartley saw red.
The midfielder looked to connect with the ball in a challenge on Chambers but presumably having used too much force in the eyes of referee Jon Moss, Bartley was dismissed once Moss had emerged from a crowd of protesting Forest players.
Captain Paul McKenna was booked for leading the posse as a crestfallen Bartley departed and his team-mates prepared to dig in and cope a man short.
Lewis McGugan fired a free-kick against colleague Marcus Tudgay and then forced Jensen to make a routine save but with Forest offering little in attack, Burnley reached the break and the chance to re-group with no major scares.
Howe opted not to make a change in personnel as the Clarets began a rearguard action epitomised by Jensen's stunning 54th-minute save from another McGugan free-kick.
Danny Fox leads the defence
Forest's top scorer is one of the Championship's deadliest set-piece exponents and thought he had scored his 13th-goal of the season when he hammed a right-footer over the Burnley wall.
But Jensen refused to be beaten and flung himself to his right to palm the ball away with Robert Earnshaw flagged offside as he headed the rebound onto the top of the bar.
It was desperate stuff from the Clarets at times but the impressive Michael Duff, wearing a fresh kit after getting bloodied by a first-half stray elbow from Tudgay, and Andre Bikey stood firm in the heart of the defence.
And Jensen more than justified his recent recall in goal with another top-class save as he dived to smother at the feet of Earnshaw.
The Clarets had limited opportunities going the other way but mid-way through the second half they almost snatched the lead.
But Bartley heads for an early bath
Ross Wallace made an instant impression after coming off the bench and when he slipped a pass through for Dean Marney, the acting captain forced Camp into a sprawling save as he directed a low shot towards the bottom corner from 22 yards.
The first goal was always going to be priceless but unfortunately for the Clarets it went Forest's way seven minutes later.
Manager Billy Davies made a double change to try and force the issue and McGoldrick made the difference with virtually his first touch.
Duff's foul just outside the side of the penalty area gave McGugan the chance to fire the ball into the danger area and as it ricocheted around the six-yard box, McGoldrick stuck out a leg to steer a close-range effort into the back of the net.
Jensen then tipped over another McGugan piledriver as Howe sent on Chris Iwelumo and Steven Thompson to try and rescue a point and leave Graham Alexander waiting to make his 1000th-career appearance.
The Clarets feel the pain of conceding
With three minutes to go Iwelumo almost delivered the goods as he met a bouncing Wallace cross with a header which a grateful Camp grabbed.
But with Burnley having to throw men forward they were caught short at the back in injury time when Earnshaw squared for McGoldrick to mis-kick home his second of the night and finally end Forest's own win drought.
Burnley: Jensen, Mears, Fox, Duff, Bikey (Thompson 86), Marney, Cork, Bartley, Eagles (Wallace 63), Delfouneso, Elliott (Iwelumo 80). Subs: Carlisle, Alexander, Duffy, Grant.
Sent off: Bartley 32
Booked: Bikey 49, Fox 65, Duff 72
Nottingham Forest: Camp, Moloney (Gunter 82), Konchesky, Chambers, Morgan, McCleary, McKenna, Moussi (Majewski 71), Tudgay (McGoldrick 71), McGugan, Earnshaw. Subs: Adebola, Boyd, Bennett, Darlow.
Booked: McKenna 32, Konchesky 51
Referee: Jon Moss