It was a second defeat in three league games and a truly dreadful performance, a culmination of negative feeling built up by yet another chaotic transfer window overseen by the club’s hierarchy.
Players were out of form and self-doubt quickly emerged as soon as things started to go wrong on the pitch, which unravelled spectacularly against Jose Mourinho’s side.
However, since that match United are unbeaten in four games and have won three of those - netting 11 goals and conceded just twice, including statement victories over PSG and RB Leipzig.
It is still early days, but there are plenty of promising signs that Solskjaer’s side have turned a corner and are back on the right track this season.
Here, Daily Star Sport assesses five season-changing decisions the Norwegian has made since the loss.
Keeping faith with De Gea
The return of Dean Henderson to Manchester United this summer once again turned the spotlight on the long-term future of David De Gea.
Henderson thrived at Sheffield United last term and penned a new five-year deal at Old Trafford, adding competition for the Spaniard.
De Gea’s form has nosedived over the past two seasons and he has been responsible for multiple high-profile errors in recent campaigns.
Whilst he was not directly at fault for any of the 11 goals conceded in the opening three games of this season’s Premier League, his communication with defence and organisation of the back-line were called into question.
Whilst there were suggestions Henderson would replace him in the line-up, De Gea has started every game since and excelled with a number of fine saves, whilst also being restored as Spain’s number one.
The presence of Henderson will no doubt have focused the Spaniard and given him the drive to improve his performances, and for now that strategy is paying off.
The two are known to be inspiring the club’s youngsters and will play a big part for the club in the seasons to come.
Persisting with Lindelof and Maguire
Much of the blame for United’s early-season struggles lay at the heart of their defence. The form of captain Harry Maguire came under particularly scrutiny, following a difficult summer away from the pitch and a total absence of form.
Maguire’s troubles continued into the international break as he was sent-off for England and Denmark.
His long-term United defensive partner Victor Lindelof did not play in the Tottenham defeat, although he was largely at fault for the loss against Crystal Palace on the opening day of the campaign.
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However, Maguire - who missed the win in Paris through injury - and Lindelof have rekindled their partnership since with just one goal conceded in those three games, which was an unfortunate Luke Shaw own goal at Newcastle.
Axel Tuanzebe starred in Paris and was tipped to become a first-team regular, but for now Maguire - who scored at Newcastle - and Lindelof - man of the match for the hosts against Chelsea - have been retained, and largely impressed.
No doubt there positions will come under scrutiny again this season, but for now their form has stabilised and they are providing the bedrock of a stable side.
Entrusting Fred and McTominay
The holding midfield duo of Fred and Scott McTominay do not win many headlines for Manchester United, but they have been influential in recent key victories.
The midfield pivot have gone about their roles efficiently in recent games; breaking up the play and recycling possession effectively.
Neither started against Tottenham, with the midfield of Nemanja Matic and Paul Pogba exposed by a direct and purposeful visiting side.
This duo provide balance and industry to Solskjaer’s midfield, in a similar way that Jordan Henderson and Georginio Wijnaldum do at Liverpool.
They are the engine room of this United side to provide a platform to their more technically talented attacking teammates.
Bold team selection v PSG
Solskjaer is not shy in switching personnel or indeed his formation, as he reverted to a 3-5-2 formation for last week’s triumph in Paris.
It was a game in which Paul Pogba was dropped to the bench, with defender Axel Tuanzebe handed his first start in a year with Alex Telles making his debut.
It was a formation which was hugely effective in allowing United to contain their opponents and play a punchy counter-attacking game, whilst also imposing themselves on possession and territory.
The selection worked a treat, with United deserved winners on the night and showing their tactical flexibility and adaptability to find success.
It is not just in starting line-ups where Solskjaer has shown his tactical acumen, but also in getting his in-game substitutions right.
This was often a criticism of his management last season - whereby he was often unable to influence games through tactical switches or substitutions in the latter stages.
Donny Van De Beek’s introduction at Newcastle helped ignite a late flurry of goals, Paul Pogba was influential after emerging from the bench in Paris and Marcus Rashford netted a hat-trick after being introduced against PSG, when Bruno Fernandes also showed his influence.
These game-altering substitutions have been enough to get United over the line in recent matches, including three late goals against Newcastle, a late winner in Paris and four goals in the latter stages against RB Leipzig.