The hundreds of Millers fans who helped clear the snow off the pitch spent the final minutes of the first half with their head in their hands as new signing Claude Davis endured a nightmare debut.
The central defender was sent off for two yellow cards in first-half added time having given away the penalty that handed Rovers the lead.
Neither side had managed a shot on target until Davis bundled over Rovers debutant Ryan Brunt and Lee Brown easily beat Andy Warrington from the spot.
Davis, already booked in the 9th minute, then brought Brunt down on the edge of the area and received his marching orders.
Worse was to follow for the home side. 18-year-old substitute Ellis Harrison doubled Rovers' advantage three minutes after his introduction with a solo run down the left which saw him beat off two defenders before sliding the ball home.
And then in the 61st minute Joe Anyinsah repeated the process down the right before beating Warrington with a powerful drive.
It was left to substitute David Noble, a former Bristol City player, to restore a little Rotherham pride in the 73rd minute with his first touch of the ball - a 25-yard power drive - but many of the home fans had already gone.