Derby had picked up three wins in a row since losing the reverse fixture at Pride Park which had put a gap of five points between the two struggling outfits.

That cushion looked like being maintained before three goals in the last 14 minutes swung it emphatically the Millers' way, leaving them just two points from safety.

This was the third attempt to play this game after the previous two had been called off following an outbreak of Covid-19 in the Rotherham camp in December and then due to Tuesday night's heavy downpour which caused waterlogging.

The 24-hour delay allowed both teams to include deadline day signings in their squads, with Derby having a quartet of newboys on the bench and Rotherham's substitutes including Lewis Wing.

The pitch had recovered overnight and the ball seemed to be zipping around as Derby created the first opportunity with Jason Knight's shot being clung on to by Viktor Johansson.

Martyn Waghorn came much closer as he acrobatically flicked Colin Kazim-Richards's header over the bar.

Michael Smith was the first to bring David Marshall into action as he took aim from 25 yards out and forced the Derby skipper into a diving save.

Jamie Lindsay should have done better when he raced through on goal but he opted to take the volley early and it flew just wide.

Max Bird was denied early in the second half after wriggling clear of a challenge on the edge of the box and curling an effort which Johansson had to parry.

Matt Olosunde then latched onto an opening at the other end but the right-back's effort from just inside the box was tame.

Derby boss Wayne Rooney brought on debutants Patrick Roberts and Lee Gregory in search of a winner and the latter spurned a great chance within minutes of entering the fray.

The Stoke loanee got ahead of his man from Nathan Byrne's cross but his header was skewed wide of goal.

That proved to be a big moment as just minutes later Rotherham were celebrating at the other end. They took a 76th minute lead with Michael Ihiekwe on hand at the back post to prod past Marshall after Wes Harding's long-range free-kick was flicked perfectly into his path by Smith.

The points were made safe in the 81st minute with Smith finishing clinically at the near post after Matt Crooks had burst down the left flank.

Ryan Giles rounded off a great night for the Millers on 88 minutes as he went on a mazy run through the Derby defence and fired powerfully into the bottom corner.