This is the new Manchester United era of happy accidents being overseen by Michael Carrick and helped by confusing officiating as they edged past Nottingham Forest. If it was not for a lack of obvious options five months ago, United and Carrick may not have been reunited, nor would they be third in the Premier League and heading back to the Champions League, on the day Bruno Fernandes equalled the all-time Premier League assist record.

Carrick has a two-year contract on the table and cannot require too much mulling over. The improving Old Trafford atmosphere was further boosted after the final home game being won partly thanks to a bizarre decision by Michael Salisbury to allow a Matheus Cunha goal to stand, on account of Bryan Mbeumo’s clear handball in the buildup being “accidental”, much to the confusion of everyone without a whistle.

Luke Shaw’s first United goal in more than three years was cancelled out by a Morato header in the second half. Within seconds of the restart after the Forest equaliser, the ball was in the back of the net but Matheus Cunha’s celebration was quietened when everyone realised Mbeumo had effectively caught the ball between his biceps and chest to tee up the Brazilian. All that was required was a simple box-ticking annulling of the goal but instead, after a miserably lengthy delay, Salisbury announced that everything was fine, much to the chagrin of the away end.

This was supposed to be a celebration of Carrick staying on and Casemiro departure but VAR and Salisbury tried to take the focus. The Carrick songs started from the first whistle, as the supporters offered their backing to the man in charge. Proceedings were slow in a game that felt like a friendly for a few minutes until Luke Shaw pounced on a defensive lapse. It was a worthy reward for being an ever-present this season after years of injury turmoil derailed the defender.

Standing tall and proud on the edge of the technical area, Carrick absorbed the occasion and what he has quickly built from the carnage of Ruben Amorim’s reign. He will, however, know that plenty of investment is needed to make the squad competitive on all fronts with an increase in demands next season.

Senne Lammens made a superb save from Morgan Gibbs-White after 21 minutes. It was a reminder that United’s recruitment has been successful this time around after many windows of overpriced duds. The Belgian’s stop instigated a counterattack, involving two more summer arrivals, Cunha and Mbeumo, the latter rounding Matz Sels, only to hit the post, before Casemiro poked wide to miss his chance of a fitting swansong.

Casemiro got his Old Trafford farewell, against one of his potential successors in Elliot Anderson. The Brazilian has become increasingly popular at United over the past four seasons but another year at the heart of the midfield looked an improbability for the 34-year-old. A Casemiro banner was unfurled before kick-off, reading “Até a morte” - to the death. It represented the Brazilian’s warrior spirit that he has shown in the good and bad times here.

Every Casemiro tackle was cheered and whenever he received possession within 30 yards of goal, there were demands of “shooooooot!” He was given a standing ovation in the 80th-minute, strolling off, clearly emotional. It should, however, be pointed out that the Brazilian is leaving with only a League Cup and an FA Cup medal in his backpocket, having been part of a muted period for United, something Carrick is here to change.

Anderson was Forest’s most influential player, creating Morato’s leveller and being a constant menace. He harassed Casemiro and Kobbie Mainoo constantly, providing the energy required to make the game more competitive.

After the controversial second, Mbeumo finished his fourth clear chance of the match from a Fernandes cross, for a record-equalling 20th assist in a season, which felt like a clincher. An irritated Forest came again as Anderson picked out Gibbs-White, whose intuitive finish set up a more tense than anticipated ending.

United won their final home game last season against Aston Villa to finish 15th, having already lost the Europa League final as the club hit rock bottom under Amorim. There was optimism things could improve then and Carrick has taken them forward and back to Europe’s top table. The apathy that shrouded United early in the campaign has dissipated but there can be no rest at Old Trafford.