Since Sir Alex Ferguson, the greatest manager to grace the Premier League, retired in May 2013, Manchester United have had a plethora of managers, none of whom have brought back one of the big two trophies to Old Trafford.

Jose Mourinho brought an EFL Cup and Europa League to United, Louis van Gaal secured an FA Cup, and Erik ten Hag lifted a Carabao Cup and another FA Cup.

David Moyes didn't last a season, Ole Gunnar Solskjær couldn't get over the line in finals, and the Rúben Amorim experiment saw United finish 15th in the Premier League table.

The furthest the club has ventured in the Champions League since 2013 is the quarter-finals, in 2013/14 under Moyes, when they lost 4-2 to Bayern Munich, and in 2018/19 under Solskjær, when Barcelona knocked United out 4-0.

However, life could have been very different had United secured their top choice target, Pep Guardiola, to take over from Sir Alex in 2013, following the latter's retirement.

Reflecting in his new book, Games of My Life, the former United boss has revealed that he often feels he made a mistake by not dining a few months earlier with Pep Guardiola.

By the time they spoke in 2012, the Spaniard had committed his future to Bayern Munich, and would then go on to secure an astonishing number of titles at Manchester City.

"Over the past ten years, I have often wondered what might have happened if the dinner I had with Pep in New York in 2012 had taken place a couple of months earlier," the legendary manager wrote.

"At the time, I hadn't decided for certain that I was going to retire. And Pep was convinced that, after achieving huge success in just four years in La Liga with a Continental treble as well as a League and Champions League double, he wanted to try life in the Bundesliga with Bayern Munich.

"If I could rewind time, we would have dined some months earlier; I would have poured plenty of Tignanello (Italian wine), and I would have tried my hardest to convince him that his future lay in Manchester. Unfortunately for us, it did. Enough said."

There has been debate of late over the legitimacy of Guardiola's achievements with Manchester City after they were found guilty of breaking the Premier League's rules on 114 occasions between 2008 and 2018, a period that laid the foundation for their recent success.

An independent panel found that the club had funneled over £900 million in sponsorship money from illegitimate sources, which was spent on signing some of the best players in world football.

However, in the book, Ferguson had nothing but praise for Guardiola dn his impact across the current generation of footballers and next generation of managers.

"Pep has set a breathtaking standard for the current generation of players or anybody aspiring to become a manager," Ferguson continued.

"Draped in Barcelona's blue and garnet from the time he was born, he had a brilliant club career and was one of the best creative midfielders in the game during the 1990s.

"During his playing days, Pep had more than a taste of success - he positively feasted on it. He also had the opportunity to play for a series of strong personalities with different approaches to managing - Johan Cruyff, Bobby Robson and Louis van Gaal.

"Pep became manager of Barcelona when he was just thirty-seven years old. When I see some of the game's biggest stars leave the field and immediately take a manager's job without much preparation or experience, my heart sinks. It often ends badly, especially for the Premier League players.

"The stakes are too high. You're right in everyone's crosshairs. The public expect that your success on the field will automatically transfer to the dugout. Former players are impatient to make the transition to the top tier. Pep Guardiola is the most celebrated example of a manager who started with a top club when he was relatively young."