Millwall were defeated 4-0 by Fulham in the Sky Bet Championship on Wednesday night at Craven Cottage.
Ivan Cavaleiro netted twice, either side of an Anthony Knockaert goal and a Aleksandar Mitrovic penalty to secure a comfortable victory for the West London side.
Lions boss Neil Harris made three changes from Saturday's win over Sheffield Wednesday at The Den, with Tom Bradshaw, Ryan Leonard and Jiri Skalak - for his first Championship start - replacing Matt Smith, Aiden O'Brien and the suspended Jed Wallace in the starting XI. Jayson Molumby stepped up to the bench.
The first half-chance of the evening went the way of Millwall, but in the third minute, after controlling Murray Wallace's throw, Ben Thompson's effort spun away from goal.
The home side began to apply pressure, however, and swung numerous crosses into the box, but the Millwall defence held firm. In the 13th minute, the opportunity for the home side to take the lead presented itself, but after Knockaert's cross found Mitrovic, the Serbian's header was tipped over the crossbar by Bartosz Bialkowski.
Just two minutes later, however, the scoring was opened as Cavaleiro was allowed to step inside and unleash an effort that gave Bialkowski no chance from just inside the penalty area.
The Lions had the chance to equalise just minutes later, but Jake Cooper headed Skalak's tempting free-kick over the bar.
With 32 minutes played The Whites doubled their lead as, after a slick passing move, Knockaert nodded home from around six yards out.
The manager opted to bring on Smith for Shaun Williams at half-time, and it was the striker who had The Lions' first attempt on goal of the second-half, but his low shot was gathered by Marcus Bettinelli. Millwall, for the first time in the game, then produced a spell of pressure on the Fulham goal, but after efforts from Mahlon Romeo and Bradshaw, Fulham's sheet remained clean.
Steven Sessegnon was then unfortunate not to further extend Fulham's lead on 52 minutes as his cross was deflected by Mahoney on to the crossbar, but The Whites had the chance to notch a third from the penalty spot after Mitrovic was brought down by the helpless Bialkowski - the Serb smashing the ball home.
Seven minutes later, it was four, as Tom Cairney's sublime pass was latched on to by Cavaleiro, who rounded Bialkowski to slot home.
Cavaleiro then looked for his hat-trick with 18 minutes remaining but found the arms of Bialkowski, before The Lions had the ball in the net through Bradshaw, but he - or Smith - was ruled to be offside from Murray Wallace's cross.
After two minutes of injury-time, referee Darren Bond blew his whistle on Millwall's first loss of the campaign - but there is a chance to put things right in just three days' time, as The Lions travel to Middlesbrough.
Fulham: Bettinelli, Mawson, Johansen, Mitrovic, Cairney (Decordova-Reid 69'), Ream, Arter (MacDonald 75'), Cavaleiro (Kamara 78'), Bryan, Knockaert, Sessegnon. Subs not used: Rodak, Le Marchand, Reed, Christie.
Scorer: Cavaleiro 15' 63', Knockaert 32', Mitrovic pen 56'
Booking: Mitrovic, Knockaert
Millwall: Bialkowski, M. Wallace, Cooper, Williams (Smith 46'), Thompson (Molumby 75'), Bradshaw, Romeo, Pearce, Leonard, Mahoney, Skalak (Ferguson 39'). Subs not used: Steele, Hutchinson, O'Brien, Bodvarsson.
Referee: Darren Bond