Millwall moved five points clear of Hull in the Sky Bet Championship play-offs as second-half goals from substitute Mihailo Ivanovic and Josh Coburn earned their side a 3-1 win at the MKM Stadium.
Ivanovic cashed in on goalkeeper Ivor Pandur's error in the 70th minute before Coburn's fierce hit eight minutes later provided Alex Neil's side with a victory that had looked highly unlikely after a one-sided first half.
The visitors opened the scoring after 14 minutes through captain Jake Cooper's instinctive volley from close range, but they were extremely fortunate to have been level at the break.
Hull, who twice struck the crossbar and also had a dubious goal disallowed in a breathless first half, equalised four minutes later when Joe Gelhardt scored his 12th goal of the season.
However, Neil's decision to replace floundering duo Zak Sturge and Tommy Watson at half-time proved a masterstroke.
Millwall were far more assured thereafter and left East Yorkshire with three points courtesy of goals from Ivanovic and Coburn.
Sturge and Watson will have been glad to have been put out of their misery at the interval as Hull bossed the first half and were a persistent nuisance along Millwall's left flank.
And it was from that side of the pitch that Kyle Joseph should have put the hosts in front.
John Lundstram did really well to beat two men before crossing into the six-yard box. Joseph had time and space to plant the ball into the back of the net - but his header struck the crossbar and rebounded to safety.
That miss proved costly as Millwall scored with their first attack of the game.
Femi Azeez's deep free-kick found Tristan Crama, who headed the ball across the face of the goal. Cooper was perfectly placed and expertly volleyed home off the underside of the crossbar.
Hull regrouped, and deservedly equalised through Gelhardt. The Leeds loan signing cut inside and then showed laudable composure to power the ball into the roof of the net from inside the penalty area.
Hull dominated for the remainder of the first half and can feel aggrieved not to have been in front at the interval.
Charlie Hughes struck the underside of the crossbar with a fine header off Regan Slater's free-kick, before Joseph saw his 30th-minute header controversially ruled out by referee David Webb.
Lundstram and Gelhardt were both denied by last-ditch blocks from Sturge and Cooper, with the resultant skirmish falling to Joseph, who headed home from inside the six-yard box.
Webb, however, adjudged Oli McBurnie had impeded goalkeeper Anthony Patterson in the build-up - even though there was minimal contact.
Millwall were, however, transformed following the introduction of Alfie Doughty and Luke Cundle at half-time.
And even when Doughty was replaced on the hour, there was a growing sense that Millwall would kick on.
And so it proved, as Ivanovic put the Lions in front when Azeez's low cross from the right slithered through Pandur's palms. The Serbian could not miss.
Hull pressed for an equaliser but were again victims of their own demise when Coburn intercepted Cody Drameh's careless crossfield pass before ramming the ball into the bottom-left corner of the net.
Hull's Sergej Jakirovic:
"I'm very shocked. When you watch it back, it is a goal.
"How has McBurnie fouled if he is in front of the goalkeeper? You can complain about VAR, about how long it takes to make a decision, but at least it's fair.
"It was a moment of change because at 2-1 it's not the same game.
"I think we played very well, maybe the best home performance since I've been here.
"This is the way we must continue. Unfortunately, we lost the game, but this is football."
Millwall's Alex Neil:
"It was a pleasing victory, but it wasn't a good performance I wasn't pleased at half-time, hence why I made two changes. We also lost Casper (De Norre) before the game, so we had to juggle things around, which wasn't perfect.
"It wasn't a great build-up going to the game - there were a lot of little fidgety bits - but that is not an excuse for the performance.
"I thought Hull were better, performance-wise, and carried a threat, but we are obviously delighted to get three points.
"What we did do is defend our box well. We always dig in and we always do the basics pretty well, and that gives you a chance.
"The points are important, but the performances are also important."
