Goals from Kieran Lee and Chris Maguire proved enough for Wednesday to pick up all three points at the City Ground.
It was Forest’s fourth defeat in a row in the league and saw them drop down to 13th in the Championship table with 31 points from 25 matches, 10 points behind sixth-placed Watford.
Stuart Pearce’s side started the season as one of the top-six contenders, but their struggles since December have seen them slip down into the bottom half of the table.
Forest are one of the biggest clubs in England and relegation from the Championship to League One is unlikely, but given their slide, it may not come as a surprise if they eventually get dragged further down.
The Forest fans were understandably frustrated with the defeat to Wednesday and took to social networking site Twitter to have their say.
Below are the best reactions.
It's worth noting that Wednesday scored 10% of their season-long goal tally against us yesterday. That is how bang average they are #nffc— Adam Watson (@Green_Adz87) January 11, 2015
I had a horrible dream last night that we lost 2-0 at home to Sheffield Wednesday #nffc— Mark Truman (@markt1977squash) January 11, 2015