As if the season hadn't already been painful enough for Liverpool fans, it ended with Manchester City winning the Champions League to seal the treble.

Historically, Liverpool and City weren't really competitors, but since the club's takeover by Sheikh Mansour in 2008, and especially during the Jürgen Klopp era, a close on-field rivalry has developed.

And it has extended beyond the boundaries of the pitch too, developing into a symbolic battle between an established giant and the nouveau riche.

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While many Reds fans would be hesitant to admit it, it would have hurt to see City land its first Champions League after years of 'where's your European Cup?' taunts on the club's visits to Anfield.

Pep Guardiola's side had already won the Premier League, overtaking Arsenal as the Gunners wilted in the face of City's robotic relentlessness, and beat local rivals Manchester United to dethrone Liverpool in the FA Cup.

And yet, even in the face of this historic achievement, a first for the millennium, there are at least five big names who could leave the Etihad this summer, as per The Athletic's Sam Lee.

Kyle Walker, a $64m (£50m/€59m) signing from Spurs in 2017, looks poised to make a shock move after growing 'unhappy' with his playing time and missing out on a place in the Champions League final XI.

Aymeric Laporte, who was a club-record $73m (£57m/€67m) addition from Athletic Bilbao in 2018, appears 'certain' to follow him out the door.

Then there's İlkay Gündoğan, bought from Borussia Dortmund for $27m (£21m/€25m) seven years ago and yet to make a decision on his future as the expiry of his contract looms. City is pushing hard to keep him but, as per the Manchester Evening News, they have had to name him on their released list to the Premier League, and he could choose to go to Barcelona (via The Athletic).

Another round of Bernardo Silva speculation is on the way as the $55m (£43m/€50m) former Monaco man considers a potential move to Paris Saint-Germain, as per Fabrizio Romano (via GOAL).

And finally, Riyad Mahrez is open to joining the Saudi league influx, five years on from his $77m (£60m/€70m) move from Leicester. He was apparently 'very disappointed' not to feature in either the FA Cup or Champions League final.

With the exception of Laporte, who found himself at the bottom of the center-half pecking order, each of those players played a key role in an all-time great season.

Gündoğan, Bernardo and Mahrez all featured inside the club's top 10 for minutes played, and Walker wasn't far behind in 12th.

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They could join the likes of João Cancelo, Raheem Sterling, Gabriel Jesus, Oleksandr Zinchenko, Ferran Torres and Leroy Sané in seeking a move away from City despite the club's bountiful success under Guardiola.

By contrast, since Philippe Coutinho left in 2018 in the final instance of Liverpool acting as a 'stepping stone', the club has only lost three key players.

We've defined this as players who have logged over 2,000 minutes in their final season as an indicator of their importance.

The only trio who pass this test are Sadio Mané, Georginio Wijnaldum and Emre Can, and even then Wijnaldum has said he wanted to stay but wasn't offered an appealing contract (via the ECHO).

The conclusion we can legitimately draw here is that Klopp is much better at keeping his players happy than Guardiola, whether that's through his rotation, his man-management skills or both.

There's an argument that the players listed simply want a new challenge after winning everything at City (the Champions League had eluded them up to this point), but you can counter that by pointing out that Gündoğan could have signed a new deal long ago, and Bernardo has seemingly been on the brink of an exit for years.

You might also question whether this is really an issue for Guardiola in light of his sustained dominance, but two of the players started against Inter in Istanbul, another came on, and the two that weren't involved have historically been vital players.

Laporte made the PFA Team of the Year in 2018/19, and Mahrez has been named the club's player of the month seven times, including twice last season.

It's unlikely that City loses all five, but even with its seemingly infinite resources, it may not be immune from the effects if two or three stars depart.

Yes, the club has the resources to recruit elite replacements, but signings are inherently laden with a degree of risk and some need time to settle rather than reaching the level of their predecessors immediately, as City has found with Jack Grealish and Kalvin Phillips in the last couple of years.

Meanwhile, there's no indication that any of the players who were truly crucial for Liverpool last season will try to leave, even though the Reds failed to even qualify for the Champions League.

Perhaps Klopp deserves credit for that, for this may be one area where he's superior to Guardiola.