Robins' men followed up the news with a lacklustre display, gonig down 1-0 in the penultimate pre-season outing before the big kick off against Lincoln City a week on Saturday.
Ricky Lambert's goal just before the hour sealed the win for Rovers in a scrappy affair.
They were hindered by the loss of Darryl Duffy early on with a hamstring injury, but neither side threatened too much until after the break.
The Millers missed first half chances through Reuben Reid and Mark Burchill, before Lambert swept home Craig Disley's ball into the corner giving Andy Warrington no chance.
Rovers nearly extended their lead as Byron Anthony headed Stuart Campbell's corner over the top, before Steve Philips saved from substitute Alex Rhodes at the other end.
As the game neared it's conclusion, Warrington, in fine form all evening, tipped Lambert's 20 yard drive to safety and Mark Hudson squandered the Millers' best chance to equalise as he fired wide.
Millers: Warrington, Lynch (Todd 76), Sharps, Joseph, Green (Tinto 76), Mills, Hudson, Harrison, P Holmes (Rhodes 67), Reid (Taylor 76), Burchill.
Rovers: Phillips, Green (Pipe 61), Igoe, Elliott (Anthony 46), Campbell, Lambert, Duffy (Riggs 6), Coles, Disley, Hughes, Lescott.