LOAN WATCH: Southampton's Sharp scores as Nottingham fall to Oldham
The on-loan Southampton striker got one back for Forest in the fifth minute of injury-time but the damage had already been done as the Latics saluted 3-2 at the City Ground to move through to the fourth round of the famous cup competition.
On own-goal from Matt Smith had Forest ahead after 13 minutes but a Robbie Simpson double and a further goal from former Everton forward Jose Baxter plus a red card to Forest's Danny Collins marked a frantic seven minutes which allowed Oldham to take a convincing 3-1 lead into the final stretch.
Sharp gave Forest some hope with his seventh goal in 10 matches but Paul Dickov's Oldham marched through to the next phase at the expense of Alex McLeish's side who have yet to win under their new boss.
Sharp has now scored a total of 10 goals in 24 outings since joining on a season-long loan from the Saints in the summer.