Doncaster slumped to their first defeat in eight games after goalkeeper Jan Budtz gifted Nottingham Forest a goal which set them on the path to victory.
Budtz was caught in two minds when Ian Breckin lobbed a ball into the box, and Kris Commns nipped in to score.
Grant Holt added the second straight after the interval, hammering home an angled drive.
Doncaster's James Coppinger scored from the spot with four minutes left after Paul Green was fouled by Sammy Clingan.
Doncaster: Budtz, Stephen Roberts, Lee, Wheater, McDaid, Price (Mulligan 79), Green, Horlock, Coppinger, Fortune-West (Neil Roberts 65), McCormack (Guy 65).
Subs Not Used: Ravenhill, Blayney.
Booked: Stephen Roberts.
Goals: Coppinger 86 pen.
Nottm Forest: Pedersen, Curtis, Breckin, Morgan, Perch, Bennett, Gary Holt, Clingan (Thompson 90), Commons, Grant Holt (Lester 88), Tyson.
Subs Not Used: Gardner, Cullip, Gamble.
Goals: Commons 25, Grant Holt 47.
Ref: E Ilderton (Tyne & Wear).