Morgan Gibbs-White scored in the 82nd minute to give Nottingham Forest its first Premier League victory over Manchester United in 29 years, effectively ending Erik ten Hag’s reign.
Marcus Rashford appeared to have saved a point for the visitors when he capitalized on a gaffe by Forest keeper Matt Turner 12 minutes from time.
However, after Turner had redeemed himself with a superb stop to deny Christian Eriksen, Forest counter-attacked and Gibbs-White scored the game-winning goal from a lovely cut-back from former United attacker Anthony Elanga.
After a sluggish first half, Nicolas Dominguez opened the scoring as new manager Nuno Espirito Santo guided Forest to back-to-back victories for the first time since their re-promotion to the Premier League.
It was another tough night for Ten Hag, this time in front of Sir Dave Brailsford, who will have a key say in United’s on-field activities following Sir Jim Ratcliffe’s 25% ownership of the Old Trafford club.
It was United’s 14th defeat of the season, their highest before the end of a calendar year since 1930-31.
While Rashford’s goal ended a six-hour wait for a Premier League goal, it means they’ve been beaten four times in December alone and might finish this round of fixtures in ninth place, just three points ahead of Chelsea.