Man United could learn how to fix a broken giant from Liverpool, Juventus and Atleti

Ferguson hoovered up a gargantuan 38 trophies during a legendary 26 year run at Old Trafford and the club has been in the wilderness ever since his 2013 departure.

His hand-picked successor, David Moyes, was on a hiding to nothing and, despite some silverware under giants of the game Louis van Gaal and Jose Mourinho, United have been downgraded from their status at the top of the game.

The 20-time Premier League and three-time Champions League winners haven't been anywhere close to challenging for either of club football's biggest prizes and look far from a turnaround any time soon.

Investment has remained competitive under their Glazer family ownership, but the trophy cabinet shows minimal bang for their considerable buck.

That marks a stark difference to many sides who have hit an all-time low, normally provoked by ownership or financial collapse, however, the results for United are still similar.

The Red Devils have spent an estimated £1billion since Ferguson's departure, showing money isn't the answer.

But what is? Well there's plenty of examples to draw upon.

A number of European giants have bottomed out way beyond United's worst nightmares, and still returned to where the Manchester club would love to be, and talkSPORT.com is here to guide you through how they did it.

Liverpool - From relegation zone to Jurgen Klopp era

It's easy to forget with the club's stability now, but Liverpool were almost plunged into administration by previous owners Tom Hicks and George Gillett before the John W. Henry-led Fenway Sports Group took control in 2010.

Liverpool were in the Premier League's relegation zone under Roy Hodgson and, while it took some time, they're now back at the very top.

Without the extraordinary backing of their state-led competition, the Reds have been able to become English and European champions, and much of that was to do with their 2015 hiring of Klopp, returning the club to its former splendour.

However, for United fans thinking their next managerial appointment could transform the club like Klopp, there's far more to the Liverpool revolution than just their head coach.

Without smart but quiet background appointments in the shape of sporting director Michael Edwards and FSG president Mike Gordon, Klopp wouldn't have been able to fix the sinking Reds.

That boardroom triumvirate formed with Klopp has given the German everything he needs for success, showing United the biggest moves could be the ones above the manager that don't make big headlines.

Juventus - From match-fixing disgrace to nine consecutive titles

There are few worse routes to rock-bottom than being relegated for match fixing, but Juventus fought back with a might that has rarely been seen in Europe's top leagues.

Juve's 2006 demotion to the second tier following their involvement in the Calciopoli match fixing scandal ended what many considered a golden era at the club, but what has followed has arguably been even more impressive.

Three different coaches helped rack up nine consecutive titles five years after they returned to the top flight but, as an example to United, this wasn't so much about coaching.

Antonio Conte and Massimiliano Allegri no doubt did splendid jobs but, as United fans will know, nothing is possible without the right heads in the dressing room.

Players such as Harry Magurie, Paul Pogba and Bruno Fernandes have taken the brunt of criticism for United's failures, but in Turin, those figures are hard to find.

Instead, the likes of Gigi Buffon, Giorgio Chiellini and Alessandro Del Piero ensured the standard didn't drop at Juve, and they came back stronger than ever.

No excuses or media pressure stopped their ascent back to titles, and United's future transfers may need to be as much about the right characters as they are about talent.

Atletico Madrid - From LaLiga relegation to first league title in 18 years

While it's easy for those outside to look at Atletico Madrid's two Champions League final defeats to Real Madrid as failures, the fact they got there is nothing short of incredible.

Relegated from the top flight in 2000, Atleti's path back to the top under president Enrique Cerezo has been a long one, but has laid the foundation to keep them there for many years to come.

Various styles of managers were tried and tested before the club struck gold with Diego Simeone in 2011 and they haven't dropped below third in the table since 2012, taking two league titles on the way, and funding a new 68,000 seater stadium.

Simeone stands out in European football for his unique, aggressive, and slightly out-dated defensive brand of football, but he's as good an example as any for United that it doesn't really matter what the vision or plan is, as long as you have one, and back it.

AC Milan - From mid-table mediocrity to back at the summit

There's only really one club that competes with Milan in terms of European royalty, with the seven-time Champions League winners creating multiple sides that dominated the competition in different eras throughout the 60s, 80s, 90s and 00s.

It's rare that the club misses when it comes to decision making, but since 2013 they've gone from kings of Europe to mid-table strugglers.

A Financial Fair Play breach saw the club banned from Europe in 2019 and, even with just Serie A to focus on, they were again average and failed to land a top-four finish.

However, they're now back and look like sticking around, particularly at the top of Serie A.

Lots of clubs try and fail by putting club legends in senior positions, but Paolo Maldini as a technical director has combined with manager Stefano Pioli and CEO Ivan Gazidis [formerly of Arsenal] to rebuild a side in need of direction.

If they didn't already know it, Pioli's virtually trophyless CV shows United that previous silverware isn't a guarantee of success, and nor should it necessarily be a prerequisite for the role.

The Rossoneri's rise under the journeyman boss - Milan is the 12th club of Pioli's managerial career - instead shows that helping a developing coach create a balanced squad can be a calm and considered route back to consistent winning.

Which path will they choose?