The Lions' entire first-team coaching staff are self-isolating following positive tests for manager Gary Rowett and two other staff members and they will have watched, from afar, their team's first home defeat of the season.
It was the perfect way for Carlos Corberan's side to bounce back after back-to-back defeats and a late flurry gave the scoreline a better reflection of the 90 minutes.
Buoyed by this, the Terriers went ahead after 18 minutes when Alex Pritchard's ball picked out Adama Diakhaby on the right and his cut-back was guided in, with the aid of a slight deflection, by Josh Koroma.
It rewarded what was a good spell from the visitors, whose pressing game was preventing Millwall from getting into their stride and creating anything of note.
The only negative for Huddersfield was that they were not able to really press home their advantage while on top as several promising attacks came to nothing.
Having been blunted in the first half, Millwall sent on towering striker Matt Smith after the restart and they started to enjoy more possession with Jed Wallace sending a long-range strike over.
Huddersfield were able to provide a threat on the counter, however, with Mbenza placing an effort from the edge of the area wide after a driving run from midfielder Lewis O'Brien.
Diakhaby then shot just off target from slightly further out with just over an hour played as the visitors began to reassert some control.
Chances continued to come for the Terriers to make the game safe, with Koroma this time being denied by Bialkowski after he had wriggled his way into some space.
Another opportunity on the break then came and went for them, as substitute Pipa shot over from 25 yards following more good work from O'Brien.
But the result was finally secured in the 89th minute when Pipa cut inside from the left before Bialkowski parried his strike straight up into the air before the ball dropped over the line.
There was still time for the visitors to add a third in stoppage time as O'Brien grabbed the goal his performance deserved by sweeping home after being teed up by Juninho Bacuna.