Luke Irelan-Hill looks at the possible successors to the Old Trafford throne.

The day has finally arrived. Sir Alex Ferguson, or Mr Manchester United, has finally decided to call it a day.

For the last 26 years, there has been no more terrifying thought for a Manchester United supporter than pondering what will happen to one of the world’s biggest clubs when Sir Alex finally steps down.

After a career in Manchester that has spanned nearly three decades, seen him accumulate 13 league titles and countless incredible landmarks, the day has come and the question on every football fans lips is who will replace the games most irreplaceable manager?

The candidates can be found below.

David Moyes

The Everton boss has spent 11 years at Goodison Park and nobody can argue that he has achieved great things in his tenure and overachieved in almost every season.

As a young manager at Preston North End, he was advised by Ferguson to resist the management role at Sheffield Wednesday and wait for a better opportunity, which arrived in the form of Everton Football Club.

More than a decade has passed and Moyes has proven himself an incredible success and has managed this on very limited resources. The Scot has always harboured higher ambitions than those he has been able to aspire to at Goodison.

His contract expires next month, he is at a crossroads in his career, and despite being linked to the Chelsea job, the opportunity to follow in the footsteps of Britain’s most successful ever football manager may be too good to turn down.

Moyes has many of the qualities that his fellow Scot values – substance, leadership, drive and willingness to give youth a chance.  The only thing missing from his CV is a trophy win and European experience, but at United he would be surrounded resources he could only dream of at Goodison.

Jose Mourninho

A natural born winner managing a club that knows nothing but winning – it could be a deadly combination.

The ‘Special One’ as he calls himself has already delivered success at every club he has managed and he has never made a secret of his admiration for Manchester United.

Despite his love affair with Chelsea and many believing a return to Stamford Bridge is imminent, surely the chance to fill the massive shoes left behind by Ferguson would be far too tempting for Mourinho to turn down.

Mourinho’s turbulent spell at Real Madrid looks all but certain to come to an end in the weeks ahead, and it would be no real surprise if Jose has already packed a bag ready to head to Old Trafford.

However there would be some concerns from many quarters if Mourinho was to take over control at Manchester United, not least his outspoken approach, familiarity with controversy and confrontational approach. And that is to say nothing of his habit for fleeting spells at clubs. David Gill, the United chief executive, was asked what qualities he would look for in potential candidates when the time comes to replace Ferguson.

Gill responded by saying the club’ values “go back in history to our heritage, to the 50s and 60s, and the last 25 years with Alex.” He added: “To continue with that, the new manager needs to understand those values and the vision for the club, and must buy into that.”

Gill was talking about a tradition started by Sir Matt Busby, resurrected by Ferguson, of encouraging young, and even home-grown, players. Whereas Mourinho has always won with proven talent and ready-made stars and his approach would appear at odds with much of what United stands for.

But, beneath it all, he is a winner – there is no doubt he is a man that can and would deliver trophies. And that, after all, is what Manchester United is all about.

Jurgen Klopp

The 45-year-old German is without doubt one of the most exciting young managers currently involved in the game. He has led Borussia Dortmund to successive Bundesliga titles before taking his brilliant to watch and attacking young side to this season’s Champions League final, Klopp has all the credentials to take United on a mould a new side to fit his own image.

However, he has committed himself to Dortmund for next season despite losing one, and probably two, of his best players to rivals and Champions League final opposition Bayern Munich. He would represent the future and, because of lack of experience in English football, pose something of a risk but there is no doubting his ability to produce exciting, attacking football teams – something all United fans would welcome.

And the rest

Many former United players have become managers, but there are three names in particular that have been discussed in recent months, and one is already in club management.

Ferguson is known to have identified Ryan Giggs as a serious candidate for the future, talking with conviction about the idea of the Welshman, or indeed Ole Gunnar Solskjaer, taking on the role at some stage in the future.

Sir Alex also talks very highly of Solskjaer, who was a great success in charge of United’s reserve team before he left two years ago to take over as coach of Molde, who he was since led to successive Norwegian titles.

And there is no forgetting about former United defender Gary Neville would you can only assume would jump at the chance to get involved in a new United coaching set-up and, perhaps one day, take on the top job himself.

There is one thing for certain; whoever does take over from Sir Alex Ferguson, they will have the eyes of the world on them. The job will be the toughest the game has seen for many a year, it may even prove impossible.

How do you solve a problem like Sir Alex? Only time will tell.

The king is dead, long live the king! (Well, not literally)