The new United record signing was dropped again by Vicente Del Bosque for next week’s friendly with Italy and many believe that the current squad will not change too much before Brazil.
The £37million man will need to find his top form to break back into the squad that he was dropped from at the back end of last year too.
Manchester City’s David Silva and Jesus Navas along with Arsenal’s Santi Cazorla appear to be Mata’s main competition for the spot on the plane to South America.
Chelsea striker Fernando Torres was also left out of the squad with Brazilian-born Blues target Diego Costa taking his place up front.
Both Torres and Mata are unlikely to be off to Brazil this summer unless they can find their top form to impress Del Bosque in what could be their last chances of playing in a World Cup finals.