Sub Nathan Delfouneso stepped off the bench to grab a dramatic injury-time winner for Blackpool to condemn Millwall to a fourth successive league defeat at Bloomfield Road.
James Henry had fired The Lions ahead on 32 minutes direct from a corner, but Thomas Ince (61mins) hauled the Seasiders level before Delfouneso lashed home a 91st-minute winner.
Even then, Millwall left-back Shane Lowry so nearly grabbed a sensational equaliser with virtually the last kick of the game, only to see his stunning strike in the fifth minute of injury-time smash against the bar - the third time The Lions were denied by the woodwork.
Millwall will play far worse and win, that is for sure, with Kenny Jackett's men left wondering just quite how they headed back down the motorway without anything to show for their efforts on an absolute quagmire of a pitch.
Jackett could not hide his disappointment afterwards saying, "I was disappointed with both the goals. Over the last 10 games we've given away too many goals and over a period of time, we've not had enough clean sheets.
Going forward we had more chances than we have for a long time. The opportunities were there for us in a spell when there haven't been.
We've lost four on the spin, whatever the ins and outs of the game are, we have still lost four games and the league form is frustrating and we will have to do something about it."
Lions boss Jackett opted for a new-look strike force with Arsenal's loanee youngster Benik Afobe partnering Rob Hulse up front as the visitors reverted to their tried and tested formation of 4-4-2.
And with just 24 seconds on the clock Millwall could have gone ahead. Afobe's first touch for his new club saw him guide a header into the path of Henry, who in return threaded a diagonal pass to Martyn Woolford as he raced into space. Woolford's inviting delivery flew across the face of goal just inches away from the onrushing Hulse.
But barely 60 seconds later Blackpool - or rather Gary Taylor-Fletcher - so nearly conjured up an opener too. There seemed to be minimal danger when the burly frontman controlled the ball chest high on the edge of the penalty area, but he turned on a sixpence and hit a dipping volley that flew a whisker wide of David Forde's right hand post.
The Lions forced a couple of corners in quick succession, but it was 12 minutes before the visitors created another decent scoring opportunity. This time it was Woolford's low shot that was fumbled by debut keeper Mark Halstead and Hulse's reaction snap-shot smacked the base of the upright before the boot of a Blackpool defender cleared the danger.
Henry curled an effort wide whilst Tiago Gomes also dragged an effort off target as the two teams traded shots, but it was Millwall who finally made the breakthrough just past the half-hour mark. Henry and Trotter looked set to combine for a short corner routine, but when Henry waved his team-mate away and promptly drove the ball in, Halstead was left grasping at thin air as it flew beyond his reach into the top corner.
The Lions went desperately close to doubling their tally three minutes before the break. On this occasion Liam Trotter's slide-rule pass picked out Hulse and the striker quite brilliantly clipped the ball over Halstead only to see his exquisite effort crash against the crossbar, the woodwork denying him for a second time in the game.
A slick, quick counter attack after 54 minutes involving Afobe and Woolford ended with Hulse directing a downward header straight into the hands of a grateful Halstead as Millwall pushed forward after the break, whilst Blackpool's Matt Phillips could count himself very lucky to stay on the pitch following a studs-up challenge on Henry that went unsighted by both referee David Webb and his assistant.
Lions keeper Forde made a great save with his feet to keep out Alex Baptiste's cross after Mark Beevers mishit his clearance, but there was nothing Forde could do to prevent Ince from hauling the home side level. The former Liverpool midfielder showed delightful footwork, picking up the ball centrally and driving forward before despatching a low shot shot that flew into the net despite keeper Forde getting a hand to the ball.
Stephen Crainey sent another effort wide before Henry worked an opening at the other end, but went for goal himself with a shot straight at Halstead when perhaps playing in unmarked sub Andy Keogh to his right, would have been the better option.
With both teams searching for a winner, the fourth official was still holding up the board to indicate four minutes of injury-time when Blackpool sub Delfouneso slipped past Adam Smith on the edge of the area, took a couple of strides forward and smashed his shot beyond Forde to put the home side 2-1 ahead.
Millwall piled on the pressure in the remaining four minutes and went agonisingly close to securing a leveller that they so deserved, only for Lowry's piledriver to crash against the bar and away in the last seconds of the match.
Jackett's men looked shattered when the final whistle blew, but despite the frustration and disappointment of losing to such a late, late goal, this was a overall decent performance that on another day would have been more than enough to have taken all three points.
Halstead, Baptiste, Cathcart, Broadfoot, Crainey, Angel, Basham, Gomes (Derbyshire, 58mins), Ince, Phillips (Delfouneso, 78mins), Taylor-Fletcher. Subs not used: Kettings, Wabara, Osbourne, Ferguson, Eccleston.
Millwall: Forde, A.Smith, Lowry, Abdou, Shittu, Beevers, Woolford (Feeney, 84mins), Trotter, Afobe (Keogh, 82mins), Hulse, Henry. Subs not used: M.Taylor, Dunne, Osborne, Marquis, Wright.
Bookings: Abdou, Beevers
Att: 12, 653 (away 727)