Millwall's hopes of avoiding relegation suffered a huge set-back as a brace of late goals from Rudy Gestede (78mins) and Jordan Rhodes (90+2mins) secured maximum points for Blackburn Rovers.
The Lions were left to rue a hatful of missed chances - and were made to pay a heavy price when Gestede lashed home the opener with just 12 minutes remaining before sub Rhodes produced a clinical low finish to leave Millwall's Championship status hanging by a thread.
Neil Harris' charges, showing two changes to the side that started at the weekend with Magaye Gueye and Ricardo Fuller in for Lee Martin and Lee Gregory, started brightly and the first chance of the game fell to Martyn Woolford, who dragged a shot wide of goal with just three minutes on the clock.
Blackburn countered moments later through Marcus Olsson, whose deep cross from the left swerved towards goal, but thankfully the ball floated wide of the far post.
There was no let-up in an entertaining opening period and on six minutes Lions skipper Alan Dunne cut in from the right and fired just wide.
Blackburn’s first sight of goal came after 13 minutes when Paul Taylor produced some nifty footwork to weave a path through the visiting defence, but he shot straight at keeper David Forde.
Both teams created good chances to break the deadlock approaching half-time as firstly Woolford's 20-yard drive was gathered by Jason Steele, while Forde flung himself across goal to push Taylor’s curling effort away.
Millwall went so close to breaking the deadlock bang on the whistle when Gueye picked out Jimmy Abdou with a delightful cross from the right flank, but the latter's glancing header drifted inches wide of the target.
Harris' men went even closer within 60 seconds of the restart. On this occasion an insightful forward pass from Dunne picked out Woolford making a smart run into the penalty area, he in turn showed tremendous control and tenacity to hook an effort goalwards from a tight angle, but Tommy Spurr positioned himself perfectly to clear off the line.
Fuller, who really caused problems with his power and pace, was a whisker away from scoring after 49 minutes when, on a quick counter-attack, he bulldozed his way down the right flank and sent over a low ball across the face of goal just begging for a Millwall boot to connect with. Frustratingly, the ball fizzed through a cluster of players and the opportunity was lost.
On 51 minutes The Lions had a lucky let-off when Chris Brown met Ben Marshall’s cross, but his looping header rattled the crossbar whilst Aiden O'Brien and Gueye both fired shots straight at keeper Steele in the home goal from promising positions.
Sub Paris Cowan-Hall could have made a hero of himself seven minutes afger replacing Gueye when he ghosted in behind Marshall and with just Steele standing between him and goal glory, dispatched an effort just too close to the keeper, who did well to save.
Blackburn brought on their 'big guns' in the shape of prolific frontman Rhodes and Tom Cairney, and the duo's introduction saw the home side over the finishing line in the final, heartbreaking, 12 minutes.
Gestede showed Millwall how it should be done when he made no mistake with his first chance of the game 12 minutes from time, crashing home Craig Conway’s inswinging cross after it was deflected into his path by Sid Nelson. It was as cruel on the impeccable Nelson as it was the team, who did not deserve to go a goal behind.
Sub Cairney saw a goalbound effort blocked moments later before O’Brien spurned a glorious chance for Millwall in the last two minutes of normal time, shooting straight at Steele with the goal at his mercy after he had been played in by sub Gary Taylor-Fletcher.
Taylor-Fletcher was left hanging his head in despair as he spurned another chance to haul The Lions level, this time arrowing a drive wide of the target fron 14 yards, and with the visitors pressing forward desperately searching for an equaliser there was always a danger that they would be caught on the counter-attack.
Almost inevitably it was that man Rhodes who compounded Millwall’s misery in the 92nd-minute, racing on to a forward pass and calmly slotting home his 19th of the season.
Blackburn Rovers: Steele, Spurr, Kilgallon (Lenihan, 37mins), Brown (Rhodes, 70mins), Marshall, Olsson, Taylor (Cairney,70mins) Spearing, Evans, Conway, Gestede. Subs not used: Eastwood, Henley, Williamson, O'Sullivan.
Gestede (78mins), Rhodes (90+2mins)
Forde, Dunne, Harding (Taylor-Fletcher,83mins) Abdou, Nelson, Beevers, Gueye (Cowan-Hall, 60mins), Bailey, O'Brien, Fuller (Gregory, 60mins), Woolford. Subs not used: Archer, Hooiveld, Martin, Powell.