Liam Lawrence fired home a 77th-minute penalty as Portsmouth condemned Millwall to their second home defeat in three games in a dour Den encounter.
There really was little entertainment produced from either team in a scrappy match that struggled to get out of first gear, especially in a mediocre first 45 minutes.
Lawrence's crisply struck spot-kick that sent David Forde the wrong way was a rare moment of quality on a forgettable night for Kenny Jackett's side.
"We were very one dimensional today," said Kenny. "We went long too often looking for Steve Morison and were too predictable.
We can do a lot better than that. I was disappointed with our play, we weren't constructive enough and didn't create enough.
We huffed and puffed and from my point of view I was very disappointed. We can play a lot better, we need to and we will make sure that we do so."
Lions boss Jackett kept faith with the side that beat Crystal Palace on Saturday, although he did welcome Liam Trotter and Alan Dunne back to the squad following a three and one match suspension respectively, replacing John Marquis and Andy Frampton on the bench.
Although it took just 65 seconds for Millwall to register their first half-chance of the game courtesy of Steve Morison's first-time drive from a Hackett cross that flew wide, scoring opportunities were scarce in a poor opening half.
Carl Dickinson went into the ref's book on four minutes for a crude bodycheck on Hackett and seven minutes later Darren Carter saw his low shot blocked by Jamie Ashdown in the visiting goal.
At the other end a super tackle by Tamika Mkandawire averted the danger, extending his boot to somehow win possession from Hayden Mullins as he broke into the penalty area.
Thereafter Pompey, fresh from three wins in their previous four starts, posed as little an attacking threat as Millwall in the opening half as the game limped towards the break.
Even so, the visitors could have taken the lead on the stroke of half-time when Scott Barron was caught in possession, Nugent sprinted through and a combination of Mkandawire and Darren Ward did just enough to put him off his stride, the latter eventually clearing for a corner.
The start of the second period saw Trotter replace Mkandawire in midfield, but it was Portsmouth who started with more purpose with Jon Utaka getting his feet in a tangle in front of goal seconds after the restart, before he then curled an effort narrowly wide.
Nugent then hit a first-time volley from Dave Kitson's flick-on over the bar before Millwall threatened themselves, with Hackett's drive from a Barron free-kick blocked and the loose ball headed on to the foot of the post by Trotter from a yard out. However, even if his effort had gone in it would have been ruled out with the linesman already flagging for offside.
Dunne came on for Tony Craig on 62 minutes and he nearly marked his arrival in sensational style, hitting a 25-yard screamer that skimmed the bar.
Morison then hit a low shot straight at Ashdown as The Lions tried to get some attacking momentum going, but no sooner than they threatened to do so than Pompey were handed a gilt-edged opportunity to score when Hackett tripped Nugent in the area. Lawrence made no mistake with a perfect penalty despatched into the bottom left hand corner.
Millwall nearly levelled with what would have been an extraordinary goal six minutes later when the bounce from Darren Ward's hopeful long ball nearly caught out keeper Ashdown, who tipped the ball over the bar for a corner.
Unfortunately that was the last real occasion Ashdown was called into action as The Lions struggled to make any headway going forward.
Millwall: Forde, Mkandawire (Trotter, 46mins), Craig (Dunne, 62mins), Abdou, Robinson, Ward, Barron, Carter (90+1mins), Morison, T.Robinson (Lisbie, 71mins), Hackett. Subs not used: Mildenhall, Harris, Schofield, Henry.
Bookings: Mkandawire (31mins), Hackett (77mins), Carter (90+1mins)
Portsmouth: Ashdown, Rocha (Ward, 34mins), Sonko, Dickinson, Halford, Brown, Mullins, Lawrence, Utaka (Kanu, 66mins), Nugent (Hughes, 90+2mins), Kitson. Subs not used: Flahavan, Ciftci.
Bookings: Dickinson (4mins), Kitson (84mins)
Scorer: Lawrence (77mins, pen)
Ref: K. Woolmer
Att: 12,095 (away 1,170)