Alex Ferguson's decision to step down as Manchester United manager after more than a quarter of a century in charge leaves the club's hierarchy with the unenviable task of replacing the Scot, given his phenomenal success at Old Trafford.
Ferguson has won more than 30 trophies, including 13 English league championships and two European Cups. It is a record that most managers might wilt under given the level of expectation that will inevitably accompany Ferguson's successor.
"It's impossible to emulate Ferguson and deliver what he has done," according to former Monaco technical director and chief executive Tor-Kristian Karlsen.
"The brief for manager is to keep winning trophies. But United want to re-establish themselves as the No. 1 club in the world and they are a long way from that," Karlsen told CNN.
"The club is a massive worldwide brand and is now judged on its European performance. On a worldwide basis the Champions League is the Holy Grail.
"Perhaps the one criticism that could be made of the current squad is that it doesn't have a Lionel Messi, a Cristiano Ronaldo or a Radamel Falcao."
Jose Mourinho and David Moyes are two of the the potential candidates in the frame to fill Ferguson's shoes -- CNN profiles the duo below and asks Karlsen to give a boardroom view on the two men's chances at Old Trafford.
Mourinho has been heavily backed to succeed Ferguson despite hinting at a return to Chelsea, but Everton manager David Moyes is the favorite to take over from the 71-year-old Scot.
Appointed by the Liverpool-based club in March 2002, Moyes is very much in the Ferguson mold.
Both were born in Glasgow, though Ferguson played for Rangers while Moyes featured for city rivals Celtic at the start of his playing career.
The steely-eyed, taciturn Moyes is now the third longest-serving manager in the English Premier League, behind Ferguson and Arsenal's Arsene Wenger.
Despite a lack of financial resources, Everton have consistently exceeded expectations under Moyes and in 2005 the club qualified for the Champions League, while also reaching the FA Cup final four years later.
Prior to joining Everton, Moyes managed Preston North End, winning promotion from the third tier of English football to the brink of the Premier League.
The question mark against the 50-year-old is that he has never won any of the three major English trophies -- the Premier League, the FA Cup and the League Cup.
Remarkably his Everton side has never been able to win at Manchester United, Chelsea, Arsenal or Liverpool in 44 attempts.
His record in the transfer market is mixed. While Marouane Fellaini and Kevin Mirallas have been notable successes, the likes of Per Kroldrup, Andy van der Meyde and Andy Johnson were underwhelming acquisitions.
How would he cope with a bigger budget and better players at his disposal?
There is also the question of Moyes' relationship with one of United's star players -- Wayne Rooney.
In 2008, the Everton manager accepted "substantial" undisclosed libel damages when he sued Rooney, his co-author Hunter Davies and HarperCollins, the publishers of "Wayne Rooney -- My Story So Far," following allegations that he leaked details of a confidential conversation with the player.
A year later Rooney phoned Moyes personally to apologize.
If the United board do plump for Moyes, they will not have to pay any compensation as the Scot's Everton contract runs out at the end of the season and no agreement has been reached over a new deal.
Karlsen's verdict: "Moyes is the favorite, but I think he is the conservative option.
"If Moyes is appointed, the club would be in good hands. He's a balanced and sensible option.
"I don't think he would have a problem in taking charge of a club of United's size. He would also have the advantage of Ferguson potentially mentoring him.