Lionel Messi playing for a club that isn't Barcelona would never have been envisagable, but such as been the nature of 2020. Widespread reports broke out on Tuesday claiming that Barcelona's imperious captain has decided to part ways with the club after over two decades in Catalunya. And if that wasn't enough of a shocker, there's even more to it.Marcelo Belcher, one of the most reliable journalists in Spain and the man who broke the news of Neymar leaving for Paris Saint-Germain, was the first to report that Messi is set to leave Barcelona. Belcher also claims that the prolific Argentine has already chosen his next club as well — Pep Guardiola's Manchester City.Marcelo Belcher, the man who broke the Messi news first, saying Messi has decided he wants to play for Manchester City for Pep Guardiola https://t.co/HNuykD9edD— Jonas Giæver (@CheGiaevara) August 26, 2020Messi and Guardiola worked together between 2008 and 2012 and won an astonishing 14 trophies in those four years, including an unprecedented sextuple, two UEFA Champions Leagues, and other honours. The six-time Ballon d'Or winner won four of his six awards in these years, winning them in successive years under Guardiola.The combination of the Argentine and the Catalan has already proven to be one of the most illustrious player-manager duos of all time at Barcelona. Now, if Belcher, The Athletic, and several top-tier football insiders are to be believed, the legendary pair could be reunited once again, but in Manchester as opposed to Catalunya.On that note, we take a look at how Manchester City could line up behind Lionel Messi should he join the former champions and different ways they could set up in attack.Goalkeeper: Ederson MoraesEderson won the Golden Glove in 2019/20Despite his high-profile errors in the recent past, Manchester City aren't expected to make any significant changes in the goalkeeping department ahead of the 2020/21 season. Ederson has been a reliable figure for a large part of his City career, making crucial saves and adding another dimension to their build-up play.The Brazilian is well-set to retain the number one spot at the Etihad for years to come as Guardiola's go-to keeper.DefenceRight-back: Kyle WalkerWalker in action for Manchester CityKyle Walker has been one of the most important players for Guardiola's defence since he arrived at the club in 2017. The Englishman, one of the quickest and most robust full-backs in the league, has played a vital role for the Catalan in various systems and varying roles. His pace has been a critical component to help City recover whenever they've been caught off-guard on the counter.Whether it is to provide width or play as an inverted full-back to maintain their defensive structure, Walker will be a crucial player for the foreseeable future.Centre-backs: Aymeric Laporte and Nathan AkeLaporte is Manchester City's most reliable defenderWith Eric Garcia all set to leave City either this year or the next, Nathan Ake is all but certain to replace the Spaniard in the heart of their defence. The likes of John Stones and Nico Otamendi have fallen down the pecking order at the Etihad and the fact that City splashed approximately £40m on Ake is enough to suggest that the versatile defender will have an important role to play.Aymeric Laporte is Guardiola's leader at the back and is, by some distance, their best central defender. The former Athletic Bilbao man is one of the most elegant yet effective centre-halves in the world, let alone the league. His absence has been felt by City, who have conceded 12 league goals more than they did last year in 2018/19 with a fully fit Laporte.Strong rumours are suggesting that City will purchase Kalidou Koulibaly this summer, and if that goes through, Laporte will be expected to partner the Senegalese.Left-back: Joao CanceloCancelo has adapted well to playing as a left-backThe former champions made Benjamin Mendy the world's most expensive specialist left-back in 2017, but the Frenchman has left too much to be desired since then. The left-back has hardly ever been available for City due to recurring injuries, and Joao Cancelo has shown that he can comfortably play at left-back after a string of impressive displays, particularly in the UCL.The Portuguese, should he remain at the club for the 2020/21 campaign, will be expected to resume his duties at left-back.Also read: 5 Greatest career achievements of Lionel Messi