Darren Ferguson's side looked to be coasting to victory at local rivals Burnley on Saturday evening before a trio of late goals for the home side gave them the most unlikely of wins.
While blasting referee Kevin Friend for his decision to send-off Billy Jones, Ferguson admitted that his side should never have lost the game.
"In terms of football there's only one team that's played today but we've got nothing out of it," was his verdict.
"There's a very disappointed dressing room. That's four defeats for the season now; I don't know how we've lost that many because we don't deserve it."
Forest gave themselves too much to do at Deepdale last season, falling three goals behind in the first 32 minutes before a second-half fightback pulled the score back to 3-2.