The Red Devils fell to an embarrassing 4-1 away loss at Watford - their fifth defeat in seven Premier League games.
Joshua King put the Hornets ahead on the half hour mark before Ismaila Sarr doubled their lead just before the half-time whistle.
Donny van de Beek came off the bench before the restart and made an immediate impact as his 50th minute goal gave the visitors hope.
However, instead of a second-half comeback, United crumbled. Harry Maguire received two yellow cards in a space of seven minutes as the visitors went down to 10 men for the final 20 minutes.
Watford capitalised and bagged two further efforts from Joao Pedro and Emmanuel Dennis to seal a memorable 4-1 victory.
Following the full-time whistle, Solskjaer approached the visiting supporters to apologise for the performance. As it turns out, it was his final wave goodbye. Here are the main contenders to take over the managerial post at Old Trafford.
After the success he has brought to Leicester City, Brendan Rodgers is the favourite to replace Solskjaer. He's been among the favourites for plenty of managerial vacancies during his time at the King Power, but could he seal a move away this time around?
Since 2019, Rodgers has made the Foxes one of the best teams in the Premier League and reignited the conversation about which clubs actually form the so-called 'top six'.
Last season he guided Leicester to their first-ever FA Cup following a 1-0 win over Chelsea at Wembley. He also won the Community Shield with a win over Manchester City at the start of this current season.
Since that win over the Cityzens, things haven't gone as smoothly for the Foxes. Before United's capitulation against Watford, Leicester also fell to a heavy defeat against Chelsea - their fifth loss of the season.
Earlier in his managerial career, Rodgers enjoyed spells at Celtic and Liverpool. Despite many successes, it's his failed title bid at Anfield which may give United fans cold feet with regards to his potential appointment at Old Trafford.
What's more, the 48-year-old's links with arch-rivals Liverpool could also scupper his chances of becoming the next Manchester United manager. Although those rules don't always apply, just ask Rafa Benitez.
During his reign at Los Blancos - across two separate spells - Zidane won three Champions Leagues and two La Liga titles. The Frenchman has been linked with multiple jobs, including Newcastle United, Paris Saint-Germain and France.
Zizou would be a Hollywood appointment for Man United but they have already tried that route and failed with big names such as Louis van Gaal and Jose Mourinho.
A man who is always linked with the Man United role is Mauricio Pochettino. Following the dismissal of Jose Mourinho, the Argentine was favourite to replace him in the Old Trafford dugout.
Instead, Pochettino remained at Tottenham and was eventually sacked in 2020 with Mourinho taking over. At present, the 49-year-old is the manager of the PSG super team and has the joy of managing Lionel Messi, Neymar and Kylian Mbappe on a daily basis.
Question is, what would entice him away from Parc des Princes? Pochettino has been able to assemble the Harlem Globetrotters of soccer and is fighting for silverware on all fronts.
A move to Manchester United would leave him battling for the top four at best. Not exactly an attractive proposition.
Erik ten Hag
During his time as Ajax boss, Erik ten Hag won two Eredivisie titles and guided them to the Champions League semi-final in 2019.
He has been impressive during his time with the Dutch champions but is an outside choice for United.
The move would be a blessing for the likes of Donny van de Beek who was a Ballon d'Or nominee under Ten Hag's tutorship at Ajax.
The 51-year-old might not be a glamour signing but considering his long list of achievements. It's no surprise to see him in the running.
In the summer, Julian Nagelsmann took over at Bayern Munich and they currently sit top of the Bundesliga - although it hardly means anything in the German league.
A Bundesliga title is an expected minimum at Bayern, as is a good run in the Champions League.
They have made a superb start in Europe's top-tier competition, winning all three games with 12 goals scored and none conceded. It is highly unlikely that Nagelsmann would leave Bayern at this stage of his first season there.
Nevertheless, the bookmakers have got him on the list at around the 33/1 mark.
It couldn't happen, could it?
Gareth Southgate has made the English public fall in love with the national team once again.
In 2018 he took England to the World Cup semi-final and then at the delayed European Championship in 2021, they made it to their first major tournament final since 1966.
Southgate has held the position since 2016 which some would consider a long time, especially in the modern era when managers can last less than a year.
If football does come home in 2022 then Southgate may step away from his position but that might be too late as far as Manchester United are concerned.