By Tom Blow Lionel Messi, Xavi, Carlos Puyol, Pep Guardiola, Andres Iniesta, Sergio Busquets, Victor Valdes, Thiago Alcantara, Pedro… The list of superstars to graduate from Barcelona’s La Masia academy is long – too long to list in one article. Every club in Europe wants to snatch a talent from their famous youth set-up when they become available – and Manchester United are no exception. Back in 2020, United persuaded Marc Juardo, a 16-year-old right-back, to leave the Spanish sun for Manchester. It was a transfer that left Barcelona chiefs furious, as the La Liga giants tried to tie him do…