Goals from Lee Gregory, Mahlon Romeo and Jake Cooper secured an important home win for Millwall as they defeated Sheffield United 3-1 in the Sky Bet Championship on Saturday afternoon.
Gregory scored his third of the campaign to give The Lions the lead, before David Brooks equalised for The Blades.
The Lions had the last laugh, however, as defenders Romeo and Cooper eased Millwall to victory.
Boss Neil Harris made three changes from last Saturday's 1-0 defeat at Fulham, as Romeo, Jed Wallace - returning from suspension - and Gregory returned to the side at the expense of the suspended Conor McLaughlin, Fred Onyedinma and Tom Elliott.
As ever, Millwall started the brighter in front of their home fans and carved out a half-chance on 5 minutes, but the ball wouldn't drop for Gregory on the edge of the six-yard box after Wallace's pass found the frontman.
John Lundstram fashioned The Blades' opening opportunity of the afternoon four minutes later, but his shot cannoned off Brooks and fortunately bounced wide.
Sheffield United rightfully had a penalty appeal waved away on 11 minutes as Brooks threw himself to the ground inside the box - referee Andrew Madley produced a yellow card for simulation.
In a frenetic opening period, Millwall had further half-chances through Steve Morison and Ryan Tunnicliffe, but could not convert to find that elusive goal.
On 14 minutes, however, they found it. Gregory sent Wallace away down the right-hand side with a deft header and after the winger located Morison with a delightful pass, the striker's cross seeked out the goalscorer, who turned and guided the ball into the bottom corner for his third goal of the season.
United had a golden chance to level the scoring with 22 minutes on the clock, but Brooks' effort was too weak and gratefully accepted by Jordan Archer.
Millwall were defending resolutely in what was an end-to-end encounter, whilst at the other end, George Saville forced Jamal Blackman into a reaction save as The Lions looked to double their lead.
On 42 minutes, the scoring was levelled through Brooks' neat strike on the volley. A cross found the Blade unmarked at the back post and he guided his attempt past Archer and into the opposite corner.
A neat interchange of passing nearly handed Sheffield United a second goal as the second half got underway, but, eventually, John Fleck's shot went over the crossbar.
The Blades were on top as the 60-minute mark came and went, but could only muster a shot wide from Mark Duffy as the game begun to enter its final stages.
On 66 minutes, owing to some outstanding work from Gregory, The Lions took the lead through an unlikely source in Romeo. After United looked to mount an attack, the striker tracked back and slid in superbly to win the ball - his inch-perfect pass then found the right-back, who slotted home for his first goal of the season on his first Sky Bet Championship start.
Millwall came agonisingly close to notching a third goal on 78 minutes, but Cooper just failed to make contact with the ball at the back post following Shane Ferguson's free-kick.
The Blades went three up-front in their search of an equaliser - a move that Harris looked to counter by bringing on Tony Craig, who slotted into the defence alongside Shaun Hutchinson and Cooper.
That proved obsolete within seconds, however, as Cooper crashed home Millwall's third off the crossbar, with the ball clearly bouncing over the line despite split-second indecision from referee Madley.
Late on, Aiden O'Brien made his 150th appearance for The Lions, coming on as a substitute for the excellent Wallace.
Millwall: Archer, Meredith, Hutchinson, Gregory (Thompson 76'), Ferguson (Craig 86'), Romeo, Wallace (O'Brien 90+2'), Tunnicliffe, Morison, Saville, Cooper. Subs not used: King, Mbulu, Twardek, Elliott.
Scorer: Gregory 14', Romeo 66', Cooper 87'
Sheffield United: Blackman, Stevens, Fleck, O'Connell, Basham, Lundstram (Donaldson 82'), Clarke, Carter-Vickers, Stearman (Sharp 73'), Duffy, Brooks. Subs not used: Moore, Wright, Heneghan, Lafferty, Carruthers.
Scorer: Brooks 42'
Referee: Andrew Madley
Attendance: 12,669 (1,883)