A smart finish from striker Kenneth Zohore and a late Jed Wallace penalty secured Millwall a deserved 2-0 victory at Preston.
The Lions were excellent value for their fourth success of the season to move them into the top six as they condemned Preston to another frustrating home Championship reverse.
The hosts have now lost all four of their league fixtures at Deepdale and failed to register a goal.
North End disappointed with the first opportunity of the game in the 11th minute.
Millwall defender Jake Cooper had clumsily fouled Emil Riis on the edge of his own box, only for Brad Potts to slam the resulting free-kick straight into the defensive wall.
The Lions meanwhile, with Shaun Williams, Kevin Nugent and Alex Pearce directing from pitch-side in the absence of Gary Rowett's isolating senior management team, responded with Mahlon Romeo heading on a pacey run before dragging a 20-yard strike just off target.
The visitors were beginning to get into their stride, and Zohore saw a shot deflected just wide after he had met a smart through-ball from Mason Bennett.
Bennett was again the architect minutes later, teeing up Wallace, only for the Lions' forward to fire a weak effort straight at grateful North End goalkeeper Declan Rudd.
With the London side looking resolute across the back, North End were finding it difficult to make any significant progress in their bid to try and arrest their dismal Deepdale form so far this season.
The hosts were thankful to Rudd in the 38th minute. The hugely impressive Ryan Woods played in Bennett smartly, and his curling 25-yard strike was superbly tipped over the crossbar by the flying North End keeper.
Millwall had definitely been the more enterprising of the two sides in the first half, but it remained goalless at the interval.
Preston had the first chance of the second period. Andrew Hughes leapt high to meet Ryan Ledson's corner, but headed into the side-netting.
Millwall then got the goal they had undoubtedly deserved nine minutes after the restart.
At the end of a neat move through the middle, Wallace squared a ball perfectly for West Brom loanee Zohore and he slotted his first Millwall goal past Rudd from six yards.
Now staring down the barrel at another potential home defeat, Alex Neil's side were probing but Millwall's defence was proving tough to breach.
They so nearly got through in the 69th minute. Daniel Johnson played a superbly-weighted pass into the path of sub Tom Barkhuizen, only for goalkeeper Bartosz Bialkowski to produce a brave stop from close range.
Millwall wrapped up their win with six minutes left when Jed Wallace slotted home from the spot after Barkhuizen had tripped defender Murray Wallace in the area.
What the managers said...
Preston's Alex Neil: "We didn't play well enough. To win a game you need seven or eight players to play well and I didn't think we had anywhere near enough players playing well enough tonight. These are not excuses, but we did have six lads who weren't feeling well at all yesterday.
"I had asked everyone to make me aware if anything like that happened, and to be fair they all did and all came back to say that they were fit to play. This is the situation we face at the moment. If anyone has a tickle, a cough or a sore tummy, people are thinking they've got the dreaded virus. They were all tested, and all came back negative, but whatever happens we would never risk anybody."
Millwall captain Alex Pearce: "We're all really happy and really pleased with the result. As for me, I'm proud of the lads tonight. It's been a really difficult 48 hours or so for them, and it can be a bit unsettling for some players, but they've just got on with their jobs and they've come through this game with flying colours.
"The gaffer was right there behind them, he set everything up beforehand on Zoom, and he's been in touch throughout the game, directing on tactics, asking opinions on substitutions and pretty much everything else. The gaffer has been behind it all, but it's also been a terrific team effort overall.
"The lads really stuck to their game-plan tonight. Defensively we've been very solid and we just didn't let Preston threaten us nearly enough. We were also very dangerous on the counter attack too. It was a terrific all-round effort."