Dany N'Guessan handed Millwall the perfect Christmas present with an 81st-minute winner to clinch three precious points against Portsmouth.
N'Guessan, handed his first start in 15 games, guided the ball home after Liam Trotter had knocked Liam Feeney's cross into his path to send The Den faithful wild with the game's decisive strike.
"It was a scrappy 1-0 win, but where we are in the league we will take it all day long," said a relieved Lions manager Kenny Jackett.
"In recent games we have had a lot of possession and chances, but haven't scored. I'm pleased to say that today when we controlled the second half, we did score."
The Lions deserved to shade what was a stop-start match that produced plenty of effort and endeavour, but few real scoring opportunities.
Jackett was able to welcome back midfield duo Jimmy Abdou and Liam Trotter against a Pompey outfit that threw an effective five man blanket across the middle of the park.
It proved to be a frustrating opening 45 minutes for both Millwall players and fans alike, with proceedings punctuated by some interesting decisions that kept free flowing football to a minimum.
In the opening couple of minutes striker Darius Henderson was called into action with a solid headed defensive clearance from Liam Lawrence's deep free-kick as Pompey looked for an early breakthrough.
The Lions produced a decent scoring opportunity on six minutes when Nathan Baker's great block tackle won possession in the centre circle. The left-back fed Henderson, who in turn slipped a neat ball through to N'Guessan, but he dragged his shot wide.
Millwall were forced to re-shuffle midway through the half when left-back Baker hobbled off to be replaced by Alan Dunne who slotted in to fill the right-back berth with Jack Smith switching flanks.
Jackett's men continued to try and prise an opening as Brian Howard had a shot from long range comfortably held by Stephen Henderson in the Pompey goal.
However, the visitors wasted a glorious chance past the half-hour mark when the unmarked Lawrence headed woefully wide from eight yards following an inviting delivery by Erik Huseklepp.
It was The Lions who could have opened the scoring on the stroke of half-time, but Feeney's goalbound shot was blocked by Henderson with Trotter's follow-up brilliantly blocked by Jason Pearce.
Manager Jackett brought on John Marquis for Henderson at the break, but it was Millwall who were left breathing a collective sigh of relief when great backtracking by Jimmy Abdou did enough to push Greg Halford out wide as the visitors broke five on three, and the Pompey man's final delivery into the danger zone flew wide of Steve Mildenhall's far post.
Howard saw his fierce free-kick superbly parried by Henderson but it was when Hamer Bouazza came on that Millwall produced their most effective head of steam to see them push on up to, and over, the finishing line.
Marquis lashed a shot agonisingly wide with just keeper Henderson to beat after a great threaded pass from Feeney as The Lions, roared on by the home crowd, pressed forward with real urgency and impetus.
The vital breakthrough finally came nine minutes from time courtesy of some great work by the tireless Feeney on the right, Trotter's flick and N'Guessan's clinical finish.
Pompey tried to rally, but other than a Halford free-kick that flew high and wide of the target, Millwall - led by an inspired defensive display from skipper Paul Robinson - stayed strong to hold on for a vital victory.
Millwall: Mildenhall, Smith, Baker (Dunne, 22mins), Abdou, Robinson, Lowry, Howard (Bouazza, 69mins), Trotter, N'Guessan, Henderson (Marquis, 46mins), Feeney. Subs not used: Allsop, Henry.
Booking: Lowry (68mins)
Scorer: N'Guessan (81mins)
Portsmouth: Henderson, Ward (Mokoena, 49mins), Rocha, Pearce, Lawrence, Mullins, Huseklepp (Futacs, 73mins), Halford, Mattock, Kitson, Norris. Subs not used: Ashdown, Williams, Benjani.
Booking: Huseklepp (50mins)
Ref: N. Miller
Att: 11,002 (away 692)