Millwall were 2-1 winners over Cardiff City in the Sky Bet Championship on Saturday afternoon.
Murray Wallace opened the scoring after a goalless first-half, before Mason Bennett stepped off the bench to head home and double the advantage.
Joel Bagan poked home a consolation two minutes into stoppage-time.
Gary Rowett made two changes for the visit of The Bluebirds, as Scott Malone and Jed Wallace came into the starting XI at the expense of Alex Pearce and Bennett, who both dropped to the bench.
After the Memorial Day commemorations were completed, the first action of the afternoon came in the eighth minute - but after the ball bounced around the Millwall penalty area, it was gratefully received by the clutches of Bartosz Bialkowski.
The Lions attempted to build an attack inside the first 15 minutes, but despite numerous attempts to put the ball in the box, the Cardiff defence stood firm.
Oliver Burke was centimetres from successfully chasing down Alex Smithies' dallying on the ball at the midway point of the half, before Joe Ralls' effort from outside the area was parried by Bialkowski before being cleared to safety.
Jake Cooper stretched to poke a Malone corner-kick wide as a first-half devoid of clear-cut chances rumbled on, but on 33 minutes, a through-ball was taken in his stride by Burke - Smithies was quick off his line to deny the attacker a goalscoring opportunity, however.
Jordan Hugill had the first effort of the second-half, but his strike from an acute angle was comfortable for Bialkowski. At the other end, Jed Wallace's powerful strike into the danger area was turned over by Benik Afobe, before Cardiff substitute Isaak Davies' attempt was saved by Bialkowski and Hugill stubbed the rebound wide.
Joel Bagan then beat two and found his effort deflected behind as The Bluebirds looked for the opening goal, with Hugill heading over from close range from the resulting corner. Jed Wallace then struck wide as The Lions looked to gain some momentum, and with 17 minutes to play, the deadlock was broken.
A Malone corner was swung over and evaded everyone - but not Murray Wallace, who was unmarked to head home and open the scoring.
Afobe then almost made the most of a mix-up between Smithies and Cardiff's Aden Flint, but the backline were able to scramble back and prevent the striker from getting a shot on goal.
However, with eight minutes to play, the lead was doubled as dogged play by George Saville - a replacement for Billy Mitchell - broke away to send over a deflected cross that was headed home by Bennett at the back post.
There were a few nervy final moments as Bagan prodded home from close-range to halve the deficit, but The Lions held out to claim a success in SE16.
Millwall: Bialkowski, McNamara, M. Wallace, Hutchinson, Cooper, Kieftenbeld, J. Wallace, Burke (Bennett 69'), Malone, Afobe (Evans 90'), B. Mitchell (Saville 69'). Subs not used: Long, Pearce, Mahoney, Burey.
Scorer: M. Wallace 73', Bennett 82'
Booking: M. Wallace
Cardiff City: Smithies, McGuinness, Bagan, Flint, Ralls, Hugill (Ikpeazu 74'), Wintle, Drameh, Doyle (Vaulks 76'), Harris (Davies 54'), Ng. Subs not used: Phillips, Pack, King, Denham.
Scorer: Bagan 90+2'
Referee: Stephen Martin
Attendance: 12,710 (1,118)