According to Marcelo Bechler of Esporte Interativo, Lionel Messi wants to leave Barcelona immediately after the club's embarrassing defeat in the Champions League quarterfinal. Messi's contract runs out in the summer of 2021 and rumours emerged that the Argentine is keen to move on at the end of next season.However, after Barcelona were hammered 8-2 by Bayern Munich in the Champions League, Lionel Messi is reportedly fed up of the club's lack of fight and ambition and wants a transfer immediately.BREAKING: Lionel Messi has told Barcelona that he wants to leave the club this summer, according to @marcelobechler. 😳 pic.twitter.com/EDEw6a0gjo— SPORTbible (@sportbible) August 16, 2020The Argentine is unimpressed by Barcelona's presidential situation and reportedly feels as isolated as he's ever been from the club. Josep Maria Bartomeu and Lionel Messi don't enjoy the best relationship, with the former coming under immense scrutiny in recent weeks for his squad planning and decision making. Barcelona are desperate to hold on to Lionel Messi but could have no choice but to let go of him this summer. According to a Mirror Football report, Manchester City are frontrunners for his signature, with Pep Guardiola eager to reunite with the diminutive Argentine. Due to his record-breaking wages and asking price, only a handful of clubs can afford to sign Lionel Messi from Barcelona this summer. Manchester City have flexed their financial muscle several times over the years and could look to pounce on Lionel Messi's situation at Barcelona. The Argentine's £635 million release clause is an exorbitant amount even for the Cityzens, but Guardiola's side are in pole position to land Lionel Messi and could test the waters with an offer this summer. Barcelona could be forced to sacrifice Lionel Messi to begin squad rebuildLionel Messi has been Barcelona's talisman for well over a decadeBarcelona are in desperate need of a rebuild and could be forced to cash in on their main asset in the coming months. With the likes of Sergio Busquets, Jordi Alba, Gerard Pique and Luis Suarez amongst others approaching the twilight years of their careers, the Catalans need to bring in fresh blood to galvanize the squad.The humiliation and embarrassment against Bayern in Lisbon will have consequences for the Barça squad: with few exceptions (Ter Stegen, Lenglet, De Jong and Messi), the whole team is on the market. [sport]— barcacentre (@barcacentre) August 16, 2020Lionel Messi has been the club's talisman for well over a decade now and is arguably the greatest player in the history of the game. However, his Barcelona career has turned sour in the past couple of years, due to which he could look to leave the club he joined as a teenager nearly two decades ago. Also Read: 10 best dribblers in world football at the moment