Greg Blundell hit the fastest goal of the day in just 69 seconds to help Doncaster end FA Cup heroes Oldham's nine-match unbeaten home run.
Blundell was unmarked as he swept in a cut-back from Michael McIndoe from six yards out.
Kevin Betsy and Mark Hughes missed good chances to equalise and Oldham paid when Blundell set up Jermaine McSporran to run through and finish well.
Scott Vernon pulled one back with a header but it was too late for Oldham.
Oldham: Pogliacomi, Bruce, Haining, Daniel Hall, Griffin, Croft (Killen 67), Kilkenny, Hughes, Eyres, Vernon, Betsy. Subs Not Used: Bonner, Eyre, Mildenhall, Beharall.
Goals: Vernon 87.
Doncaster: Jones, Fenton, Albrighton, Foster, Ryan, McSporran (Coppinger 90), Ravenhill (Rigoglioso 64), Green, McIndoe, Roberts, Blundell (Johnson 90).
Subs Not Used: Warrington, Beech.
Booked: Ravenhill, Albrighton.
Goals: Blundell 1, McSporran 81.
Ref: G Salisbury (Lancashire).