It did not take Doncaster long to make their numerical advantage count, as six minutes later they took the lead. James Coppinger whipped in a cross that was met by Chris Brown at the front post to head past Jonathan Bond and into the net.
David Cotterill then tried his luck from range for the hosts with a swerving shot after cutting in from the right, but his effort drifted wide of the far post.
Merkel came close to equalising for the visitors at the start of the second half when his free kick came off the bar, and from the rebound Deeney fired over.
Sharp almost restored Doncaster's lead immediately as he was picked out by Mark Duffy at the back post, but put his header over.
Paul Keegan came even closer to scoring for the home side, when he saw his low strike cleared off the line by Deeney.
Doncaster continued to look the more likely to score the next goal and Duffy saw his free kick pushed behind by Bond.
With the game heading towards a draw, Doncaster snatched all three points in stoppage time, as Duffy's long-range strike was spilled by the keeper and Sharp followed up to slot home the rebound. body check tags ::