Still unfit, he proved ineffective during the first leg against Bayern Munich and was unable to play at all during the second, as Barcelona were by the eventual champions.
Although Messi was declared match-fit for his nation's second group match against on 10 June, Martino left him on the bench once again; he replaced in the 61st minute and subsequently scored a hat-trick in 19 minutes, also starting the play which led to 's goal, as the match ended in a 5—0 victory, sealing Argentina's place in the quarter-finals of the competition; he was elected man of the match for his performance.
Juste avant le face à victoire 3-0 , Messi réalise un discours devant les socios barcelonais en annonçant qu'il fera tout pour faire revenir la à Barcelone cette année.
Lors du match d'ouverture, ils sont tenus en échec par la 1-1 malgré un très bon match de Messi.
Il termine aussi quatrième meilleur passeur du championnat avec 10 passes décisives.
Il se fait remarquer le 14 juin 2021 en inscrivant un but sur coup franc direct face au avant que la rencontre ne se finisse sur un match nul 1-1 ,.