Cardiff City came from behind to beat the Merry Millers and record their first victory in six starts.
Slack defending had gifted Rotherham goals from Stuart Talbot in the third minute and John Mullin just six minutes later to silence the home crowd.
Cardiff pulled one back in the 24th minute through Peter Thorne, Graham Kavanagh slid in a cross from Thorne to equalise seven minutes before the interval and then on the stroke of half time Robert Earnshaw gave his side the lead when he rounded the keeper before sidefooting home for his first goal in nine games.
The Bluebirds were further boosted by Paul Parry making a solid debut after joining for £75,000 from Hereford United.
Millers boss Ronnie Moore was highly critical of the way his side threw away their lead.
"We were cruising when two up, but then some poor defending let them in and we gave them three on a plate in ten minutes. After scoring those quick goals we had quietened the crowd and the game should have been over.
"If we keep defending in that way then we could go down, as playing like that we cannot expect to survive in this division. Cardiff were low on confidence and down on their knees at 2-0, but we gifted them the victory." Cardiff skipper Graham Kavanagh was delighted to at last be on the winning side.
"We are extremely relived to have won as we have struggled for a while and had a bad run. At 2-0 down we still believed we could battle through and our attacking play was much better.
"At half time the boss was still not happy especially with the sloppy defending, which we still have to sort out, but we came out in the second half in a positive frame of mind." City now travel to Bradford on Saturday looking for another victory to put them back in sight of the play-off positions.