The Barcelona playmaker's release clause is believed to have dropped down to around €18 million because he didn't feature in a minimum of 60% of the Catalan club's fixtures last term.
Manchester United are reportedly keen on exploiting that fact and are lining up a bid.
Previous reports in Spain claimed that the Spanish U21 star - who will likely feature for his country in the U21 European Championship final against Italy tonight - was weighing up his options. They are said to include a move to either Manchester United or to Bayern Munich.
However now Sport say Alcantara has made up his mind to leave Barcelona - who do not want to let him go - with Manchester United firm favourites to secure his services.
The paper claims Alcantara wants to leave Barcelona in order to gain more first team football, and to put himself in contention for a spot in Spain's squad for the 2014 World Cup.