Alan Dunne had three reasons to be cheerful as he grabbed his third goal in successive games as Millwall extended their unbeaten run under caretaker manager Willie Donachie to three games with an awayday special at Carlisle.
Midfielder Dunne, who had hit the target in The Lions' previous matches against Brentford and Rotherham United, was perfectly placed to set the visitors on their way to victory after 27 minutes and condemn Carlisle to their first home League defeat of the campaign.
Donachie was forced to reshuffle his pack with Paul Robinson ruled out with a slight hamstring strain and Ali Fuseini rested.
Danny Senda and Samy Mawene came into the side, with Mo Ross switching from right-back to partner Richard Shaw in the centre of defence.
Millwall started postively, with Alan Dunne and Chris Hackett using the flanks against a Carlisle rearguard that looked nervy in the opening exchanges.
Danny Haynes tried his luck from distance with hooked efforts that flew over, while Elliott was inches away from connecting with Hackett's teasing cross.
Carlisle had a let-off on 20 minutes when Danny Haynes' persistence put the home defence under pressure, keeper Keiren Woodward made a hash of his attempt to kick clear and the ball ricocheted off Poul Hubertz's back which the Woodward scrambled across his goal to smother at the second attempt.
Alan Dunne was left holding his head in his hands two minutes later when he somehow scooped over from five yards following a superb run and cross by the impressive Hackett.
Haynes picked up Hubertz's flick-on with his back to goal, but still maanged to turn and let fly with a fierce drive that flew over as The Lions continued to pressurise Carlisle.
Hubertz wasted a glorious opportunity to open the scoring after 25 minutes, heading Hackett's deep cross wide when unmarked at the far post.
But Millwall finally got the goal their pressure deserved after 27 minutes. Hubertz atoned for his earlier miss when he worked his way to the by-line and cut the ball back across goal. Although Haynes swung at it and missed, Dunne was perfectly placed to fire home.
But The Lions' celebrations had barely died than Carlisle were back on level terms courtesty of Jermaine Beckford's close-range finish after the visitors had failed to clear Simon Hackney's 31st-minute cross.
Back came Donachie's charges in perfect fashion and Hubertz kept his cool to capitalise on a defensive mix-up and slot The Lions 2-1 ahead from 12 yards.
Yet no sooner had the game kicked off again than Carlisle were handed - and threw away - a glorious opportunity to haul themselves level when Hubertz was penalised for handball. Up stepped Chris Lumsdon and he smacked the foot of the post with the resulting penalty before the loose ball was finally cleared.
Tony Craig was a whisker away from increasing Millwall's lead seconds before a breathtaking first-half came to an end when he won possession on the edge of the area and sent a left-foot drive a yard over with keeper Woodward grasping at thin air.
Carlisle introduced the burly Derek Holmes for Chris Billy at the break, but within seconds of the restart an elecrtifying run by Hackett casued panic in the home defence as The Lions won two corners in quick succession that were dealt with comfortably.
Haynes showed great pace to set up Hubertz and then Mawene's cross was collected by Woodward under pressure from Dunne.
Carlisle frontman Beckford was fortunate to remain on the field after 52 minutes when he hacked at Mawene, but having been booked just three minutes into his debut, the Leeds loan signing was shown considerabe leniency by referee Graham Laws, who issued a stern warning instead of a second yellow card.
But it was Millwall's turn to ride their luck when, after a period of sustained Carlisle pressure, a handball by Craig went unspotted by the officials. At the other end Haynes headed wide following a sweeping move involving sub Chris Zebroski and Hackett down the right flank and then Zebroski tested Woodward`with a low angled drive.
Even when the fourth official showed five agonising minutes of time added on, Donachie's men dug deep for one last time.
However, deep in injury-time it looked as if Carlisle had clawed a leveller when Kevin Gall's rocket shot headed towards the top corner. Somehow, Lions keeper Pidgeley stretched every sinew of muscle to tip the ball over for a corner, which Millwall cleared to finally clinch a richly deserved win.

Carlisle United: Keiren Westwood, Chris Billy (Derek Holmes, 46mins), Danny Livesey, Kevin Gray, Chris Lumsdon, Paul Thirwell, Paul Arnison, Simon Hackney, Zigor Aranalde, Jermaine Beckford, Kevin Gall. Subs not used: Anthony Williams, Simon Grand, Glenn Murray, Stephen Hindmarch.
Booking: Beckford (3mins)
Scorer: Beckford (32mins)

Millwall: Lenny Pidgeley, Mo Ross, Tony Craig, Marvin Elliott, Alan Dunne, Chris Hackett, Danny Senda (Mark Phillips, 65mins), Richard Shaw, Samy Mawene (Derek McInnes, 74mins), Poul Hubertz (Chris Zebroski, 80mins), Danny Haynes. Subs not used: Chris Day, Liam Trotter.
Bookings: Ross (39mins), Hackett (52mins), Pidgeley (68mins)
Scorers: Dunne (27mins), Hubertz (38mins)

Ref: G. Laws
Att: 8,413 (Away 513)