Here, Press Association Sport takes a look at the club's fortunes since Sir Alex Ferguson's long and successful reign came to an end in May 2013.
Best laid plans
It seemed a natural succession when Ferguson called for the United faithful to get behind new boss David Moyes when he finally called time on his trophy-laden Old Trafford career. Time, though, was a luxury his fellow Scot did not have. Being the man who followed the man was never going to be an easy job, in fact it was almost impossible – with all the best forward planning swiftly laid to waste as results on the pitch just did not stand up to the scrutiny. Former Holland boss Louis van Gaal replaced Moyes and lasted just less than two years at the club. He was sacked two days after leading United to FA Cup success in 2016 after a reign littered with speculation about his future and reports of dressing room unrest.
Ferguson's departure left a void over all of Old Trafford, but was also the opportunity to look to restructure the club, much like Arsenal did at the end of Arsene Wenger's long reign last summer. However, with no director of football in place, key decisions made in the boardroom would again ultimately play out on the pitch. The choice of managers to come in following Moyes' dismissal continued to cause debate and divide the fanbase as United's football style changed again with them.
Despite the spending power of their Premier League rivals, United have continued to invest heavily in the squad in the seasons since Ferguson left. Indeed, under Mourinho the expenditure was more than £400million – not including the 'free transfers' of the likes of Zlatan Ibrahimovic and Alexis Sanchez, both on considerable wages, Romelu Lukaku provided another statement signing, while Paul Pogba returned to Old Trafford on a club-record fee. Yet no matter how much cash has been invested, so far no manager has been able to fully recapture the team ethic which was the backbone of Ferguson's era. For every relative successful recruit, others have either failed to deliver, or not been given the time to show their true talents – Angel Di Maria and Henrikh Mkhitaryan are cases in point. The new permanent boss will, of course, want to stamp their own mark on a squad which, on current results, still needs some balance.
Rivals on the rise
For so long, Arsenal were the main rivals in the Premier League for Ferguson's United, before Roman Abramovich's arrival at Chelsea shifted the powerbase across London. Then along came Manchester City.... The transformation of the blue half of Manchester, however funded, has provided United managers with an extra sense of urgency to keep the noisy neighbours in check. Yet while City have gone on to maintain their place at the very top of the English game, United have been left playing catch up in an effort to mount a sustained title challenge since their last triumph under Ferguson in 2012–13. With Liverpool now having stepped things up again under Jurgen Klopp, the new United boss faces challenges on all sides as the Red Devils try to wrestle back their once established position of dominance.