(CNN) -- 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.
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Manchester United manager Alex Ferguson is retiring after 26 years in charge
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Everton manager David Moyes is the frontrunner to succeed Ferguson
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But one expert says Real Madrid's Jose Mourinho is the perfect choice
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Tor Kristian-Karlsen: "It's impossible to emulate Ferguson"
If the United board do plump for Moyes, they will not have to pay any compensation as the @placeholder's Everton contract runs out at the end of the season and no agreement has been reached over a new deal.