Goals from ex-Bristol City striker Paul Heffernan and James Coppinger earned Rovers their third straight win.
But for Gary Johnson's Bristol City - after eight straight defeats - they are staring a relegation battle in the face.
Doncaster paid City £125,000 in the summer and Irish striker Heffernan took just five minutes to score against his former club.
Coppinger split the defence with a ball to Heffernan whose shot beat Adriano Basso via a deflection off Osei Sankofa.
Scott Murray and Luke Wilkshire both had chances to score for Bristol, while at the other end both Lewis Guy and Michael McIndoe did well to beat the full-backs only to see their crosses cut out by Basso.
City defender Kelly Youga had a header cleared off the line by Sean Thornton five minutes before half time, while Basso then had to turn Coppinger's drive away via the crossbar in first-half stoppage time.
Stephen Brooker missed a golden opportunity to equalise on 48 minutes when he slammed the ball against the crossbar from six yards after Bas Savage's flick from a left wing cross.
Guy missed two opportunities in a minute, first when he diverted Heffernan's header goalwards and then when he was thwarted by Basso after McIndoe's through ball.
McIndoe then crossed for Coppinger who was denied by Basso, but the right winger had the last laugh on 68 minutes when his flicked header from Thornton's free-kick went in at the far post.