The Bluebirds' woes continued in a 4-1 hammering at the hands of Hull City last time out, while Neil Harris's troops were convincing 3-1 victors over Preston North End.
Match preview
Rather than clear out his locker with the doomed Bulut, former Bluebirds assistant boss Omer Riza stepped into the chair on an interim basis for the biggest job of his managerial career to date, having previously taken charge of Watford and England youth teams.
Riza's reign - however long it may last - got off to a dream start as Callum Robinson broke the deadlock against Hull at the weekend, but the Cardiff striker had only triggered a Tigers onslaught, as Mohamed Belloumi (two), Oscar Zambrano and Chris Bedia ripped the Bluebirds apart.
Riza had mixed feelings about his first match in a senior managerial capacity, claiming that the 4-1 scoreline was "harsh" but also conceding that his side were ruthlessly punished for their mistakes as they slumped to their fifth successive loss in all competitions.
Propping up the Championship standings in 24th place, Cardiff cannot rise above the relegation line no matter what happens in midweek, as the bottom-placed Bluebirds have a four-point gap to make up to both 22nd-placed Preston and 21st-placed Coventry City.
Furthermore, Cardiff's only Championship point this season was gleaned on the road, and the Bluebirds have suffered three consecutive 2-0 defeats on their own patch - should they go down on Tuesday, it will mark the first time in their history that they have lost their first four home games of a league season.
In contrast, Millwall had no difficulties sweeping aside their most recent visitors to The Den, scoring three against Preston in just 47 minutes as George Honeyman, Romain Esse and Macauley Langstaff - finally off the mark for the Championship season - made the net bulge.
Jordan Storey's consolation and a straight red card to Aidomo Emakhu were two minor blots on Millwall's notebook in the dying embers, but those two incidents paled into insignificance in the grand scheme of things as the Lions marched to their second league triumph of 2024-25.
Entrenched comfortably in mid-table thanks to their solid yet unspectacular start, Millwall sit 14th before Bristol City take on Swansea City in Sunday's showdown, and Harris's men now have some wrongs to right on their travels after making home advantage count at the weekend.
Indeed, the Lions failed to win any of their first three Championship away games of the new campaign, but Harris has seldom been outfought by his former club, avoiding defeat in each of his last four games against Cardiff as a manager.
Millwall have also been beaten in just one of their last four matches against the Bluebirds in all competitions, although that one loss did come at the Cardiff City Stadium in December 2023, where Goutas scored the only goal of the contest for the Welsh outfit.
Cardiff City Championship form:
L
D
L
L
L
L
Cardiff City form (all competitions):
D
L
L
L
L
L
Millwall Championship form:
L
D
W
L
D
W
Millwall form (all competitions):
D
L
W
L
D
W
Team News
Cardiff's cause against Hull was not helped by a pair of injuries either side of the half-time whistle, as former Manchester United protege Will Fish came off just before the break, while Callum O'Dowda had to call it a day in the 73rd minute.
Riza conceded that Fish had already reported pain in his hamstring before the game, and the 21-year-old will surely not make the cut this week after exacerbating the issue, but he could not give a definitive update on O'Dowda.
Kion Etete (leg), Ryotaro Tsunoda (muscle), Jesper Daland (ankle) and Aaron Ramsey are also missing for the hosts, but Bulut is optimistic that Manolis Siopis and Dimitrios Goutas will be fine for the midweek fixture; the latter missed the Hull loss with a personal issue.
Millwall attacker Emakhu endured arguably the most embarrassing 12 minutes of his career on Saturday - he was brought on in the 77th, was booked for diving in the 89th and then sent off for violent conduct following a clash with Robbie Brady.
The suspended Emakhu would never have started in Cardiff, though, while Tom Bradshaw (muscle), Josh Coburn (leg) and Billy Mitchell (hip) are also missing for the visitors.
However, Langstaff filled the Coburn void expertly in the win over Preston, setting up Honeyman's drive before opening his Championship account for the new campaign, and he will surely reprise his role at the tip of the attack.
Cardiff City possible starting lineup:
Alnwick; Ng, Goutas, Chambers, Collins; Ralls, Robertson; Tanner, Colwill, El Ghazi; Robinson
Millwall possible starting lineup:
Jensen; Leonard, Tanganga, Cooper, Bryan; Saville, De Norre; Esse, Honeyman, Watmore; Langstaff
We say: Cardiff City 1-2 Millwall
Despite Riza's affirmations that he saw some encouraging stuff from Cardiff in their loss to Hull, the Bluebirds' defensive deficiences are there to be exposed by a Millwall side on cloud nine.