Marvin Sordell ensured Burton Albion completed a smash-and-grab raid at The Den on Saturday afternoon as The Brewers defeated 10-man Millwall 1-0.
In a heated affair in south London, The Lions had Jed Wallace sent off early into the second-half. The defeat was Millwall's third at home in the Sky Bet Championship this season.
Millwall boss Neil Harris made four changes from Tuesday night's 2-1 defeat to Sheffield Wednesday, with the attacking trio of Aiden O'Brien, Lee Gregory and Steve Morison returning to the line-up at the expense of Shane Ferguson - suffering from illness - Tom Elliott and Fred Onyedinma.
Meanwhile, Tony Craig stepped in for the suspended Jake Cooper.
The first opportunity of the afternoon fell the way of The Lions, but after just two minutes, O'Brien curled comfortably into the arms of Stephen Bywater.
The home side kept probing for the opening goal early on and had efforts from George Saville and Conor McLaughlin blocked. The former also had a free-kick sail onto the roof of the net on 22 minutes as Millwall dominated the opening exchanges.
On the half-hour mark, Craig's long ball found Morison, who nodded down into the path of Jed Wallace. However, the winger's cross was tantalisingly taken away from the onrushing Gregory by Bywater.
Millwall's best chance of the half came on 43 minutes. Morison's cross found Wallace at the back post - the former Wolves man volleyed towards goal, only for his attempt to be put over the bar by O'Brien. Seconds later, Wallace fluffed his lines from close range as The Lions did everything but score.
The biggest talking point of the game to date came on 59 minutes, as referee Tony Harrington showed Jed Wallace a straight red card for bringing down Tom Flanagan. The tackle was cynical, but perhaps warranted a yellow card at best.
O'Brien headed wide on 61 minutes as the atmosphere inside The Den inevitably went up a notch. Harris freshened things up by introducing Ben Thompson and Elliott into the play for O'Brien and Morison, but on 70 minutes - perhaps predictably - Burton took the lead through Sordell's strike.
Millwall kept up their attempts to register on the scoresheet but could only find the back of the lower tier through Ryan Tunnicliffe's effort on 79 minutes.
Onyedinma was thrown on in a final roll of the dice by Harris, but it was not to be as Gregory struck the post with the final shot of the game.
Millwall: Archer, McLaughlin, Meredith (Onyedinma 87'), Hutchinson, Craig, Gregory, Wallace, Tunnicliffe, Morison (Elliott 64'), O'Brien (Thompson 64'), Saville. Subs not used: Martin, Romeo, Twardek, Mbulu.
Sent Off: Wallace
Burton Albion: Bywater, McFadzean, Turner, Murphy, Lund, Scannell (Akins 64'), Dyer, Flanagan (Warnock 71'), Sordell (Varney 83'), Palmer, Buxton. Subs not used: Ripley, Allen, Naylor, Miller.
Scorer: Sordell 70'
Booking: Turner, Bywater
Attendance: 11,507 (208)
Referee: Tony Harrington