He said: "The one thing that Rotherham didn't show was class or respect from above. I think the chairman was a bit disrespectful.

"We are quick enough to have a go at fans for using (bad) language or being offensive on the side but you don't expect it from the chairman. I wouldn't expect it from our owners or our board.

"It's a bit disappointing but I suppose he works in different ways to us."

The defeat drags Derby back into bother at the bottom of the table, just two points ahead of Rotherham in the final relegation spot.

The game, initially scheduled for December before a Covid-19 outbreak in the Rotherham camp and then for Tuesday night before an astonishing downpour prior to kick-off, burst into life late on after a long stalemate.

Derby debutant Lee Gregory ought to have put the visitors in front but he headed wide from Nathan Byrne's cross and moments later, the Millers were on their way to a famous win.

The first came through Michael Ihiekwe who was unmarked at the back post to fire past David Marshall after Michael Smith had won the header from Wes Harding's long freekick.

Smith doubled the lead himself as he was at the near post to fire in clinically following Matt Crooks' run down the left wing.

And the win was rounded off in resounding fashion by loanee Ryan Giles who smashed into the bottom corner after going on a solo run through a tiring Derby backline.

On the game, Rooney added: "I think the first goal was always going to be important. I feel if we score that then we go and win the game. Lee had a great opportunity and should score."

Warne said: "We didn't start as well as I would have liked. I thought we showed them a bit too much respect.

"In the end I thought we could have scored more. It was an edgy game but to come away with a clean sheet and three goals, we're really pleased.

"The players have been magnificent, even in defeats, fortunately tonight the ball bounced for us kindly in the six-yard box and we took our chances.

"We have had three wins out of five. With this amount of games left, we have our destiny in our own hands."