Ful-time from the Cherry Red Record Stadium
Aiden O'Brien set the tone for an entertaining game with a sumptuous fifth-minute strike to put Millwall ahead, only for former Lion Lyle Taylor to level just five minutes later.
Steve Morison's 12th goal of the season restored Millwall's lead before half-time, but back came The Dons for a second time to claim a share of the spoils with a 51st-minute Tom Elliott equaliser.
A draw was just about the right result on an afternoon where both teams gave their all, and the football was at times played at a breathtaking pace.
Millwall responded and immediately threatened with Lee Gregory's cute delivery from the right headed behind for a corner. Although Shaun Williams' delivery was dealt with by the home defence, there was little anyone could do to prevent O'Brien breaking the deadlock on five minutes with a stunning 25-yarder that gave James Shea no chance in the home goal.
That lead lasted just five minutes, however, and The Dons were back on level terms when Taylor pulled away from his marker to flick Dean Parrett's corner in to the back of the net from close range.
Shea was called into action midway through the half when Onyedinma and Shaun Cummings set up Ben Thompson in a central position, but the midfielder's low 20-yard drive was comfortably collected.
The keeper had to be alert again on 29 minutes with a super save. A quick throw from Cummings found Onyedinma, his low cross was met by Gregory but Shea reacted smartly to parry low to his right and avert the danger.
Another fine Millwall move, this time down the left, ended in frustration when Steve Morison was unable to direct his header on target from O'Brien's inviting delivery.
Gregory then looked to try and latch onto Thompson's forward pass, but despite being clearly impeded by former Lions defender Paul Robinson as he threatened to break through, no free-kick was awarded as the visitors began to turn the screw.
Millwall were rewarded for their spell of pressure five minutes before the break. Morison capitalised on a poor defensive header and, using all his wily experience, guided the loose ball over the head of Shea with a sublime finish to hand Harris' men a 2-1 lead.
That second goal sparked a positive reaction from The Dons who piled on the pressure but found no joy as The Lions went in holding a one-goal advantage at half-time.
In fact Harris' men could have added a third goal deep in injury-time when the pace and power of Onyedinma sliced through the Wimbledon defence, his perfectly weighted slide-rule pass picked out Gregory who was through on goal but denied by a strong, last-ditch challenge from Darius Charles.
Within seconds of the restart, and from a near identical position, Lions skipper Tony Craig was equally well placed to made a trademark sliding tackle and nick the ball off the toes of George Francomb as the Dons man broke into the danger zone.
Another free-kick from Parrett on 49 minutes nearly conjured an equaliser for the home side, but defender Charles, steaming in at the back post, powered a free header over the bar.
Millwall failed to heed the early second-half warnings and found themselves pegged back for a second time with 51 minutes on the clock; Taylor was the provider with some neat footwork on the right and his delivery was met by the head of Elliott, who steered his effort beyond the reach of Archer.
The Dons really had their tails up and squandered a great chance to edge ahead just moments later, only for Francomb to head over the bar from eight yards with the goal at his mercy.
Taylor was lucky not to be punished for a late challenge on Shaun Hutchinson on the halfway line that went unsighted by the officials, and The Lions bench were frustrated twice in the next couple of minutes, firstly when Shea got down low to somehow scoop out a deflected shot on the line to prevent a near certain goal and then again, when defender Byron Webster was grappled to the ground for a clear penalty.
A flurry of corners, all fired into the mix by Williams, forced some desperate defending by The Dons, but Neal Ardley's side soaked up the pressure before enjoying a decent spell of possession themselves.
It took a stunning save by Archer to deny Wimbledon a third goal with 13 minutes remaining, the keeper flinging himself low to his right to keep out Reeves' effort at point-blank range.
There was a real sense that this ding-dong match had a goal left in it entering the final 10 minutes with both teams thrashing it out in search of that decisive strike to claim all three points.
Lions sub David Worrall tried his luck with a left-foot drive from 18 yards that flew narrowly over the bar but it was Wimbledon who finished on the front foot, forcing a couple of corners that were well dealt with by Millwall to ensure honours were even at the end of a cracking encounter.
Scorers: Taylor (10'), Elliott (51')
Millwall: Archer, Cummimgs, Hutchinson, Craig, Williams, Thompson (Butcher, 86'), Gregory, Onyedinma, Webster, Morison, O'Brien (Worrall, 69'). Subs not used: King, Ferguson, Abdou, Smith, Romeo.
Booking: Morison (73')
Scorers: O'Brien (5'), Morison (40')
Att: 4,742 (away 654)
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