ROTHERHAM United were stunned by a three-goal, second-half salvo from Fleetwood Town that sent them crashing to a League One defeat at AESSEAL New York Stadium this afternoon.
The Millers led 2-1 at half-time and looked to be heading into the play-off places but capitulated after the break to slump to a shock loss.
The introduction of loanee Will Grigg as a substitute couldn't revive Paul Warne's men who had looked to be in such a strong position when they went in at the interval.
There were boos from some home followers at the end of a reverse that left them in 13th place in the table.
A quiet start meant that the game had to wait until the 13th minute before the first real effort on goal, Chiedozie Ogbene thumping the ball wide as he drove forward on the right.
Rotherham came close to taking the lead seven minutes later as Michael Ihiekwe rose to meet Kieran Sadlier's corner only for his downward head to bounce up and be tipped away by former Millers goalkeeper Alex Cairns.
However, the home side found themselves a goal down against the run of play on 24 minutes when the visitors broke and Callum Morton flashed in a shot from the tightest of angles.
The Millers responded with a Ben Wiles shot comfortably dealt with by Cairns and New York was a quiet place in the late-summer sun.
Michael Smith was high and wide after a neat turn just outside the box as Rotherham struggled to create openings against dogged opponents but was much closer with a 37th-minute header, from Sadlier's free-kick, that went just the wrong side of the post.
He finally got it right soon afterwards, despatching Wes Harding's long throw past Cairns with his head.
Moments later, New York broke into 39th-minute applause in memory of late Millers fan Adam Dewick.
Rotherham hadn't been at their best but deserved to be level, and then they merited the lead they took deep into first-half stoppage time.
It has been one-way traffic for ten minutes when Ogbene was pulled back by Callum Camps and Sadlier stepped up to send Cairns the wrong way from the spot.
The player's penalty miss at the same stage of the Sheffield Wednesday derby three weeks ago must have been playing on his mind and he showed real nerve to tuck the ball away.
Winger Ogene was fit again after a hamstring injury and came straight back into the side while Freddie Ladapo kept his place up front.
That meant new boy Grigg - like Ladapo, a scorer in midweek at Doncaster Rovers in the 6-0 EFL Trophy rout - was named among the substitutes.
Sadlier had been in fine form in the last two matches and was rewarded with a left-flank role in the starting 11.
Max Clark fired wide as Fleetwood threatened at the start of the second half through Morton's determined running before Sadlier's cross wasn't far away from floating in at the back post.
An equaliser arrived along with controversy in the 54th minute when Ged Garner tucked the ball past Viktor Johansson and his goal was allowed to stand as the offside protests howled around New York.
Worse was to follow when Rotherham fell behind just past the hour mark. Danny Andrews' stunning free-kick had pace and power and flew past the outstretched Johansson's despairing right hand.
Smith curled an effort off target as the Millers tried to hit back once more but it was Town who scored again, amid more offside shouts, when Camps beat Johansson after the keeper had just made a good save from Garner.
This hadn't been in the script and home fans couldn't believe what they were witnessing as the away supporters chanted: "We want five."
Rotherham thought they were about to cut the deficit but sub Rarmani Edmonds-Green directed the ball from close in, then Cairns had to be alert when a low Wiles cross almost sneaked in at the far post.
The Millers queried two of the Fleetwood goals but they had defended poorly throughout the second period and were the cause of their own downfall.
A Ladapo shot almost squeezed in in stoppage time but by then the contest was well over.
Rotherham (3-5-2): Viktor Johansson; Michael Ihiekwe, Richard Wood (Rarmani Edmonds-Green 66), Wes Harding; Chiedozie Ogbene, Jamie Lindsay (Will Grigg 73), Ollie Rathbone (Dan Barlaser 66), Ben Wiles, Kieran Sadlier; Freddie Ladapo, Michael Smith. Subs not used: Josh Vickers, Joe Mattock, Hakeem Odoffin, Josh Kayode.
Fleetwood (3-5-2): Alex Cairns; Darnell Johnson (Max Clark 20, Paddy Lane 70), Tom Clarke, James Hill; Callum Johnson, Callum Camps, Jordan Rossiter, Harrison Biggins, Danny Andrew; Ged Garner, Callum Morton (Ryan Edmondson 84). Subs not used: Billy Crellin, Joe Garner, Jay Matete, Carl Johnston.
Goals: Smith 38, Sadlier pen 45+3 (Rotherham); Morton 24, Garner 54, Andrew 61, Camps 70 (Fleetwood).
Referee: Craig Hicks (Surrey).
Attendance: 8,463 (216).