Never before had United trailed by two goals inside four minutes of a Premier League match, but they rallied as Christian Eriksen pulled one back from a Marcus Rashford cross.
Casemiro wasted a glorious chance to level but made amends shortly after half-time when turning home at the end of a clever free-kick routine.
Manchester United had a unbelievbale start against Nottingham Forest
Taiwo Awoniyi opened the scoring after just two minutes
Willy Boly then doubled the lead in the fourth minute
Worrall’s dismissal for denying Fernandes a goalscoring opportunity gave United extra pep in their step, with the skipper soon scoring from the winner from the spot after Danilo was adjudged to have brought down Rashford.
From a corner that followed an early Antony shot, Steve Cooper’s men cleared and Morgan Gibbs-White headed on. Awoniyi showed more hunger and strength than Rashford to win the ball inside his own half, roaring forwards and keeping his cool under pressure as he got close to goal, sitting down Andre Onana before prodding past him.
It was a fantastic Forest start that got even better in the fourth minute. Gibbs-White sent in a free-kick from the right and seemingly unsighted Boly turned home with a headed attempt that beat Onana and stunned Old Trafford.
“You’re getting sacked in the morning” chanted the Forest fans as the Old Trafford faithful called for their owners to sell up.
United looked punch drunk but eventually regained a modicum of composure, reducing the deficit in the 17th minute.
United started the second half far better than the first and equalised in the 52nd minute from a clever free-kick routine.
Forest were caught napping when Fernandes played over to Rashford, whose clipped cross was glanced back across goal by the Portuguese for Casemiro to score.
Old Trafford erupted and it was so nearly immediately 3-2, with Antony cutting onto his favoured left foot and whipping a beautiful strike that Matt Turner did well to stop.
The skipper drew a foul from counterpart Worrall in the 67th minute and referee Stuart Attwell brandished a red card having adjudged to him have denied a goalscoring opportunity.
The VAR ratified the decision, just as he did when Danilo caught Rashford in the box.
Fernandes stepped up to lash home low past Turner in the 76th minute as “Bruno, Bruno,” echoed around a rocking Old Trafford.
Forest were now a man and a goal down, but they continued to push. Onana acrobatically denied Boly but United shut up shop, with players leaving to cheers and anti-Glazer chants.