After the manner of their last two performances there was always going to be a come down for Rotherham.
The Millers had put on two high-intensity displays in the space of four days to earn back-to-back home draws against Stoke and Bristol City, having done so against the Robins with eight players unavailable.
And the game against Birmingham was simply one too far for Paul Warne's men, who were downed by a Lukas Jutkiewicz hat-trick in a 3-1 loss at St Andrew's.
Of course, playing away contributed to their downfall and their miserable record on the road needs no further examination other than to say it now stands at six defeats from six this season and 31 without a win at this level in total.
They did at least give their long-suffering travelling support a goal to savour, when Jon Taylor ended a 437-minute away drought in the second half, but they are no nearer finding a solution to their dreadful away form.
Still, being hamstrung by injuries did not help, though, as Warne was forced again to send a patched up side out, with Will Vaulks playing at centre-back and Michael Smith and Ryan Manning playing through injuries.
“Playing on Wednesday night did take its toll, they looked jaded, that's the first time I have seen a few of my senior pros look tired at the end,” Warne said.
“We have had six or seven out for a while, today two started that weren't fit, I just think it was possibly a game too far.
“But I do think it was an opportunity wasted, if we had come here with a stronger team I think we would have had a much more positive result.”
The game was effectively decided in the space of three first-half minutes as Jutkiewicz capitalised on two rare errors from Marek Rodak.
In the 20th minute Rodak could only claw a header into the net when it ought to have been a routine save and then he fumbled Gary Gardner's shot, which allowed Jutkiewicz to score the rebound.
The former Everton striker, who the Millers tried to sign in 2016, then completed a first career hat-trick on the hour when he drilled a low free-kick into the bottom corner.
Taylor did at least score his side's first away goal since the opening day of the season when he converted the impressive Kyle Vassell's cross, but it was the familiar taste of defeat for the injury-hit Millers.
Birmingham: Camp, Colin, Morrison (Roberts 74), Dean, Pedersen, Jota, Kieftenbeld, Gardner, Maghoma Mahoney 73), Jutkiewicz, Adams (Lubula 89)
Unused subs: Trueman, Solomon-Otabor, Harding, Lakin
Rotherham: Rodak, Jones, Ajayi, Vaulks, Mattock, Taylor, Palmer (Vyner 88) Manning (Wiles 63), Newell (Vassell 55), Williams, Smith
Unused subs: Price, Forde, Onariase, Lewthwaite
Referee: Keith Stroud
Attendance: 19,795 (759 Rotherham fans)