Lionel Messi has told Barcelona that he wants to leave the club this summer, sources have confirmed to ESPN.

The club confirmed to ESPN Deportes’ Jordi Blanco on Tuesday that they were notified by Messi of his decision by sending a burofax, a service used in Spain to urgently dispatch a document that requires proof to third parties.

Messi, 33, has a contract until 2021 but has grown disappointed with events on and off the pitch at Camp Nou in recent months. The 8-2 Champions League humiliation at the hands of eventual winners Bayern Munich proved the final straw and he has now informed the club of his desire to embark on a new challenge following a first trophy-less season since 2007-08.

Coach Quique Setien was sacked after the Bayern loss and Messi met with his replacement Ronald Koeman last week, telling him that he had doubts about his future in Catalonia. After several days of further reflection, Messi has now decided he wants to spend the final years of his career away from Barca, who he first joined almost 20 years ago as a teenager.

On Monday, ESPN revealed that Manchester City are already looking into the feasibility of signing the Argentine forward. The Premier League side are crunching the numbers that would be involved in the deal to see if they would be able to make the signing without breaking financial fair play rules.

Barca have stressed over the last week that they want Messi to be the pillar of Koeman’s side and that any club wanting him would have to pay his €700 million release clause. However, some board members have told ESPN they would be open to selling if Messi were to push hard enough for a move and if it allowed Koeman more funds to invest in the rebuild of the squad.

It remains to be seen if Barca will now be open to negotiating with interested parties following Messi’s request to leave the club. Very few teams would be able to offer Messi what he wants on the pitch — success in the Champions League — and, at the same time, match his wages as the best paid player in the world.

Messi, the six-time World Player of the Year, has considered leaving Barcelona before but has never previously taken his desire to leave to the club this far. He is conscious that at 33 he won’t have many more opportunities to add to the four European Cups he’s already won and has decided he will have a better chance of more silverware elsewhere after a string of disappointments with Barca.