Managers are, most often than not, the driving force behind a club's campaign. Right from cherry-picking the players that should be signed, to forging the tactics the team runs with, managers frequently possess a lot of power within a club and are expected to wield it a way most beneficial to the club.
Now, while most managers dream of establishing themselves and setting up a legacy, only a fractional few actually manage to execute their plans to perfection. As a result, not a lot of managers succeed in spending long careers with a single club.
Sometimes, a manager's departure boils down to personal wishes, while the rest depends on factors such as the equation between manager and management, or the accomplishment of targets laid down for a manager.
Modern-day clubs have frequently been impatient with managers, often replacing former ones with newer ones in a matter of heartbeats, for a plethora of reasons. Conversely, managers have also begun to shockingly call time on their career at a particular club, again, for a number of reasons.
On that note, here is a look at the top 5 surprising managerial exits that we have seen thus far:
#5 Kevin Keegan - Newcastle United
In 1992, languishing at the bottom of the table in England's Second Division, Newcastle United stared at the possibility of relegation to the Third Division for the first time ever when they brought in Kevin Keegan to replace outgoing manager Ossie Ardiles.
For someone who had spent 8 seasons outside the game, having hung up his boots in 1985 claiming to never want a managerial role, naturally, not much was initially expected from Keegan, who took over the reins of the club during their darkest days.
What followed, stunned most. Keegan didn't just lead Newcastle's resurgence in the Second Division, he led them to the limelight in the Premier League. After surviving in the Second Division, Newcastle went on to win Division One the very next season, earning a promotion to the Premier League.
In the next 4 years under Keegan, Newcastle rose to the top of the Premier League, finishing 3rd, 6th, 2nd and 2nd in the 1993-94,1994-95, 1995-96 and 1996-97 seasons respectively. Further, Keegan was also responsible for bringing in club legend, Alan Shearer, in 1996, for a then world-record fee of £15 million.
For all terms and purposes, things couldn't have been better at the Tyneside club, which is why the world was stunned when Keegan unexpectedly announced that he would be leaving the club at the end of the 1996-97 season.
While the real reasons behind his exit are still unknown, several rumours claim that it was because a long-term commitment was going to be demanded of him - something he felt he wasn't ready for. Other rumours claim that it was because of the toll that the unsuccessful league challenge took on him.
Regardless, considering the circumstances Newcastle United were in, it was a shocking decision to leave from the English tactician. Notably, he returned to the club's helm in January 2008, albeit hanging around for only a few months before controversially leaving for good.
#4 Marcelo Bielsa - Marseille and Lazio
Known for his eccentricity, Marcelo Bielsa features on this list for not one stunning departure, but two unexpected ones. In 2 consecutive stints. Beat that.
Named the manager of Marseille on a two-year contract in May 2014, Bielsa helmed the French side for 41 games across all competitions, winning 21 and holding a win record of 51.22% before stunningly calling quits on his time at Marseille on 8th August 2015, after losing just the first game of the 2015-16 season.
A year later, in July 2016, he was appointed the manager of Lazio and despite everything falling into place, the Argentinian seemingly had a change of heart in the last minute and terminated his contract just two days after taking up the job. Eccentric indeed.
Subsequently, he was sued for a sum of €50 million by Lazio for the breach in contract.
#3 Pep Guardiola - Barcelona
Appointed to coach Barcelona's B team in June 2007, Pep Guardiola led the side to the 2008 Segunda División B playoffs, which they eventually won, thereby earning promotion. Soon after, in May 2008, Guardiola was picked to replace Frank Rijkaard as the coach of the senior team.
The rest, as they say, is history.
Guardiola went on to spend 4 seasons at the club, from July 2008 and June 2012, winning 14 major titles along the way (including 3 La Liga titles and 2 UEFA Champions League titles), becoming the most successful manager in Barcelona's history. Notably, he won the treble in his very first season, before infamously winning the sextuple soon after.
Apart from leading Barcelona to titles, he also played a crucial role in Lionel Messi's rise to prominence, utilising the Argentinian to perfection. In April 2012, Barcelona found themselves knocked out of the UEFA Champions League after a 2-3 loss (on aggregate) to Chelsea in the semi-finals of the tournament.
Just 3 days later, Guardiola decided to draw the curtains on his time at Barcelona, citing exhaustion as the deciding factor, claiming that his time at the Catalan club had felt like an eternity.
What astonished most, was his willingness to terminate the exciting rivalry that the world had come to witness between himself and then Real Madrid manager, Jose Mourinho - perhaps even the rivalry of the decade.
With things going the way they were, few expected Guardiola to put an end to his Barcelona managerial career, but as we've come to learn over time, Pep Guardiola does what Pep Guardiola pleases.
Departing the club with a staggering win record of 72.5% after 247 games in charge, Guardiola decided to relocate to New York for a year-long sabbatical before going on to conquer the Bundesliga with Bayern Munich and more recently, the Premier League with Manchester City.
#2 Sir Alex Ferguson - Manchester United
Widely recognised as the greatest manager of all time, Sir Alex Ferguson's celebrated career saw him become a legendary figure in not just English football, but football in general.
In a managerial career that spanned a total of 39 years, the Scot spent 27 years at United, leading the Red Devils to 13 Premier League titles and 2 UEFA Champions League titles among the 38 major titles that he won with Manchester United, with a win percentage of 59.7 after 1,500 games in charge.
In May 2013, just months after managing his 1000th league game and 100th UEFA Champions League in charge of Manchester United, Sir Alex Ferguson shocked the world by announcing his decision to call quits on his career at the end of the 2012-2013 season - a decision that had reportedly been born in December 2012.
The general consensus was that Sir Alex desired to end his managerial career while still on a high, and that's exactly what he did. In his last season at the club's helm, the spectacular Scot led the Red Devils to their 13th Premier League title (20th English league title) before bringing his managerial career to an end in a move that many defined as the "end of an era".
What was most surprising about his retirement was the fact that he chose to end it on a high while he could've easily sustained it in the years to come had he really chosen to.
As they say, "You either die a hero or live long enough to see yourself become the villain", and in all honesty, Sir Alex Ferguson is probably the greatest managerial hero that the sport has seen, and his surprising, yet perfectly timed exit only cemented that fact.
#1 Zinedine Zidane - Madrid
Coming to more recent and trending matters, Zinedine Zidane tops this list of unexpected managerial candidates after he announced his decision to step down as the Real Madrid manager just days after leading Los Blancos to their historically unprecedented third consecutive UEFA Champions League title.
Appointed in January 2016, Zidane has indeed left his mark on the club's rich history, winning 9 major titles in a mere span of two-and-a-half years.
While the 2017-18 season may not have turned out exactly how the club and its fans would've liked (Real Madrid struggled in La Liga and Copa del Rey), winning 3 back-to-back UEFA Champions League titles is no small feat, and that's precisely what makes this exit so very unexpected.
There are some managers who are asked to leave their respective clubs. Then, there are some managers who enjoy little success before bidding farewell. The best kind of managers leave on their own time, after successful gigs with their clubs.
And then there's Zinedine Zidane. The man who made history - the man who accomplished what no other individual on the planet has - only to walk away soon after.
To be fair though, the French legend came, saw, and conquered all there was to conquer, leading the biggest club in the world rather ably, winning 69.80% of the 149 games he managed while simultaneously juggling a plethora of giant-sized egos on the side.
Several people across the world will, unfortunately, attribute his success to the fact that he had the best team in the world at his disposal.
But make no mistake, Zidane may have been lucky to have been handed the reigns of a team like Real Madrid, but unlike most managers before him who wilted under the pressure, the Frenchman didn't just visit the Sun in all its heat - he made it his own before returning unscathed.