Blackpool defeated Millwall 1-0 in the Sky Bet Championship at Bloomfield Road on Saturday afternoon.
Shayne Lavery was the match-winner as The Lions lost out in FY1.
Gary Rowett made two enforced changes to his starting line-up for the trip, with injured duo Tom Bradshaw and Sheyi Ojo replaced by Maikel Kieftenbeld and Mason Bennett.
New signing Oliver Burke, meanwhile, took his place on a bench which included Hayden Muller, Tyler Burey and Zak Lovelace.
The opening stages saw The Lions claim a lot of the possession in the midfield, but without creating any real chances that would test Dan Grimshaw in the Blackpool goal.
At the other end, Josh Bowler was to be the man who would cause Millwall most of their first-half problems, but the defence were able to deal with whatever came their way, keeping their sheet clean at the break.
With 19 minutes on the clock came the first opportunity of the game - and it went the way of the hosts. Bowler's deflected effort looked to be heading in, but Bartosz Bialkowski was able to stick out a leg and divert the ball wide in a superb save.
Benik Afobe, Bennett, Bowler and Lavery all traded half-chances as the half wore on, with a big chance for Millwall falling at the feet of Murray Wallace four minutes from half-time, but after Jake Cooper nodded on a free-kick into his path, the defender's first-time effort rolled past the far post.
Lavery's attempt early in the second-half was deflected over the crossbar, before Callum Connolly and Gary Madine both tried their luck to open the scoring, but to no avail.
On 55 minutes, however, the deadlock was broken as Lavery took advantage of a loose ball to power home from inside the area.
Rowett responded by handing Burke his debut alongside bringing Burey into proceedings, but it was The Tangerines who could have scored the next goal - Murray Wallace, however, executed a fantastic last-ditch challenge to prevent Madine from scoring.
Burey was Millwall's bright spark as the game ticked towards its conclusion, but after the winger danced through the Blackpool defence and curled an effort on goal on 79 minutes, Grimshaw had to extend his arm to tip the ball wide.
Two further chances - from Burey and Shaun Hutchinson - followed in stoppage-time, but The Lions slipped to defeat.
Blackpool: Grimshaw, Connolly, Bowler, Dougall, Madine, Lavery (Yates 78'), Ekpiteta, Hamilton (Dale 89'), Keogh, Garbutt (Gabriel 62'), Sterling. Subs not used: Moore, Stewart, Casey, Beesley.
Scorer: Lavery 55'
Millwall: Bialkowski, McNamara, M. Wallace, Hutchinson, Cooper, Kieftenbeld, Malone (Mahoney 75'), Bennett (Burke 59'), Afobe, B. Mitchell, Evans (Burey 59'). Subs not used: Long, Thompson, Muller, Lovelace.
Referee: David Webb