Neil Harris inspired Millwall to their joint-biggest win of the season and League One survival as The Lions brushed aside promotion-chasing Carlisle United at The Den.
Chopper, back in the starting line-up after sitting out the last couple of matches, marked what could be his last game for The Lions at The Den with a Man of the Match winning display and a crucial second goal sandwiched between efforts from Jay Simpson (42mins) and Tony Craig (64mins).
But it would be harsh to single out any one player for particular praise because to a man, this was as dogged, determined and adventurous a display as Kenny Jackett's side have produced this season.
The timing of this performance was perfect in what was a match Millwall simply could not afford to lose.
Boss Jackett was dealt a blow less than half an hour before kick-off when Lewis Grabban pulled out with a tight hamstring, so Bas Savage stepped in to partner Harris up front with Ryan Smith taking his place on the bench.
It was Carlisle who took the early initiative and a fifth-minute free-kick from Danny Graham flashed a matter of inches wide of Rhys Evans' post before Andy Frampton made the first of a number of perfectly-timed tackles to deny pacey winger Cleveland Taylor.
But after a slightly tentative start Millwall, roared on by truly magnificent vocal support from the home fans, overcame those early nerves and settled into their stride.
Jem Karacan's shot was fumbled by Keiren Westwood with Savage denied by the keeper as he prepared to pounce on the loose ball, whilst Simpson's first real aggressive run at the visiting defence saw Danny Livesey nearly volley the ball into his own net.
Harris sent a trademark curler wide, Paul Robinson twice had drives from Craig corners held by Westwood and then Frampton's goal-bound header was parried as The Lions pressed in search of the breakthrough.
Another Harris effort was parried for a corner by the busy Westwood before Savage stretched his long legs to get a bit of the ball, but could not direct it into the net as Millwall kept battering away at the Carlisle defence.
Something had to give, and it duly did three minutes before the break. Danny Senda's deep ball was perfectly laid back by Harris into the path of Simpson, who swung out his right boot and hit a stinging first-time shot into the bottom corner to spark wild celebrations amongst The Den faithful.
The Lions were forced to make a change within five minutes of the restart, however, when the outstanding Frampton hobbled off injured to be replaced by Marcus Bignot at left-back.
Sixty seconds Karacan fired over and Simpson then lashed wide as Jackett's men continued to press for a second, killer goal.
Cometh the hour, cometh the man - and when Harris weaved his way into the area, Livesey made a desperate lunge and sent the striker sprawling. Cue red card for Livesey and penalty for Harris, who was in no mood to miss and duly despatched a clinical spot-kick into the bottom left-hand corner.
Things went from bad to worse for 10-man Carlisle just nine minutes later. Ahmet Brkovic swung over a corner from the left, Harris headed back across goal and there was the towering Craig to head home from close range and spark scenes of utter jubilation.
Such was Millwall's dominanation that further goals could have followed. A Harris overhead kick flashed wide, Simpson fired wide and then Harris again, hit a stinging first-time effort that Westwood somehow got a hand to to push around the post.
Brkovic and Harris tried their luck as The Lions peppered the Carlisle goal without further joy. But by then the damage had already been done - and the final whistle was greeted, more than anything, by utter relief that a truly topsy-turvy season has seen The Lions avoid the unthinkable drop to League Two with a game to spare.
Enjoy your night!

Millwall: Evans, Senda, Frampton (Bignot, 50mins), Laird, Robinson, Craig, Brkovic, Karacan, Harris, Savage*, Simpson. Subs not used: Edwards, Smith*, Martin, Fuseini.
Scorers: Simpson (42mins), Harris (54mins, pen), Craig (64mins)

Carlisle United: Westwood, Bridge-Wilkinson, Livesey, Murphy, Lumsdon, Graham, Arnison, Hackney, Horwood, Dobie (Campion, 59mins), Taylor (Madine, 46mins). Subs not used: Howarth, Thirlwell, Smith.
Booking: Lumsdon (55mins)
Sending off: Livesey (54mins)

Ref: Jon Moss
Att: 10,075 (away 1,174)

* Change from line-up. Lewis Grabban pulled out injured after the warm-up