MILLWALL twice had the lead at Elland Road as Leeds recovered from a missed penalty before scoring a late winner in a relentlessly dramatic Championship clash.
Ben Thompson headed Millwall in front in the 10th minute and David Martin preserved the lead by saving Patrick Bamford's penalty nine minutes later.
Leeds were level 11 minutes before half-time, Pablo Hernandez finishing Luke Ayling's cross low past Martin's right glove.
Millwall were awarded a penalty 11 minutes into the second half and Ben Marshall fired home from 12 yards for his first goal since his return from Norwich.
Marcelo Bielsa's side reacted again, and in the 71st minute Barry Douglas crossed for Ayling to head past Martin.
It was from the same side that they went in front with eight minutes left, and Hernandez had his second from Tyler Roberts' cross.
A dramatic comeback for the second season in a row in this fixture, but this time Millwall on the wrong side of it.
They will be kicking themselves after not only leading twice but being within touching distance of what would have been a very valuable point.
Millwall appeared to be doing most things right when they led 2-1, but then the vulnerability that had been evident on the right side of their defence came back to haunt them.
That wasn't necessarily Mahlon Romeo's fault, more that Leeds repeatedly overloaded in attack on that side, and it eventually paid off for them.
Martin got his redemptive moment early on after his error against Brighton in the FA Cup, but he could do little for Leeds' goals, the first he has conceded in the league for Millwall.
Without Shaun Williams on the pitch, Marshall confidently scored the penalty, and the Lions were ideally placed for three points.
But Bielsa made attacking changes and Leeds as they have done so often this season they committed to all-out attack chasing the goals they needed to go second.
They got them, and both times their bench celebrated exuberantly, looking like it could have caused a repeat of scenes at The Den earlier in the season.
It didn't come to that, as the majority of a sold-out Elland Road erupted on the final whistle.
The brutal fact is that Millwall blew another lead this season, and just can't move away from danger. The only consolations were another good performance, and Rotherham's defeat at Derby.
Neil Harris made one change to the side that won at Birmingham in their last league game, James Meredith replacing the suspended Shane Ferguson at left-back.
Ryan Leonard started as the deepest midfielder, with Thompson getting up to support lone striker Lee Gregory.
4-1-3-1-1: Martin; Romeo, Pearce, Cooper, Meredith; Leonard; Wallace, Tunnicliffe, Marshall; Thompson; Gregory.
It was Millwall that looked like the side chasing promotion early on at Elland Road.
The returning Marshall saw an early shot saved by Bailey Peacock-Farrell and then Millwall constructed a delightful move with Thompson at the heart of it. After receiving Gregory's chested pass, Thompson changed direction in midfield before sniping forward and finding Wallace. The winger then cleverly cut inside from the right and shot left-footed, forcing Peacock-Farrell to save for a corner.
There was some concern when Meredith was booked so early for a late foul on Kalvin Phillips, but Thompson soon silenced all of Elland Road except the corner of the West Stand where Millwall fans were housed.
Romeo deserved great credit for not giving up on what appeared a lost cause, the right-back digging out a cross into the centre of the box where Thompson arrived at pace to bury a header past Peacock-Farrell.
Leeds were handed a way back in when Wallace fouled Ezgjan Alioski. Martin dived left, Bamford hit his penalty close to the centre, but the goalkeeper blocked with his legs.
Martin then brilliantly saved low from Jack Harrison who had got through following a quick exchange of passes.
Millwall then only had themselves to blame as they were caught on the counter following their own counter that broke down when Wallace had two options in Gregory and Ryan Tunnicliffe but over-hit his pass trying to find the latter. Moments later right-back Ayling was in Millwall's box to pick out Hernandez, who swept a low finish past Martin.
The hosts were on top, the away side struggling to cope with Harrison's pace and crossing from the left, as well as Alioski's surges from left-back. Martin did well to hold a fierce shot from Tyler Roberts as Elland Road found its voice.
Leeds brought on Douglas for Alioski at the break, fresh attacking energy for Romeo to worry about, but instead it was his brilliant surge from right-back that set his side away on a rapid break. Wallace took over and found Marshall in so much space arriving in the box. The chance appeared gone as he cut inside, but Liam Cooper's trailing leg sent the winger to the turf. Marshall took his eye off the ball on the spot only to glance at the referee, before sending Peacock-Farrell the wrong way.
The action didn't relent. Pontus Jansson took out Wallace and then reacted to something, as players from both sides came together. Jansson was booked and soon taken off by Bielsa, Phillips moving to centre-back to accommodate Jack Clarke.
There was a hint that the ball may have gone wide as Leeds pressed in Millwall's box, but Douglas didn't hesitate, and Ayling delivered an emphatic headed finish.
Leeds' winner came from the same side as Roberts crossed and Hernandez slammed home.
Image: Millwall FC