It all came good for the Millers in the 88th minute when Ian Sharps crashed a shot against the crossbar and summer signing Warne - back for his second spell with the south Yorkshire club - turned home the loose ball.
"Paul coming on shook people up a bit and we certainly needed it. It was good to see him back in a Rotherham shirt in a competitive game because that is how I remember him and he has always worked his socks off," said Robins.
"We didn't pass the ball well and we looked a little bit like rabbits in the headlights in the early part of the game.
"There were a few nerves which I didn't expect because we've been good all through pre-season and I certainly needed to change it at half-time because I wasn't getting anything in terms of work-rate up front."