[5][6]The coach's statements instigated Real Madrid to sign the player to a professional contract[7] and, subsequently, Mateos was called for the first match of the campaign against Mallorca.

[8] After the departure of Rafael van der Vaart and Royston Drenthe, to Tottenham Hotspur and Hércules respectively, he was promoted to the first team, being awarded the number 15 shirt previously worn by the latter.

[9][10] Mateos made his official debut for Real Madrid on 23 November 2010, playing ten minutes in the 4–0 away win over Ajax in the group stage of the UEFA Champions League; after the match, he said: "I will never forget this day.

[14] In the summer, however, he moved to Real Zaragoza also on loan for one season,[15] making his top-flight debut on 11 September in a 0–0 draw at Rayo Vallecano,[16] but the spell was marred by injury.

On 29 July 2015, Mateos joined Orlando City of the Major League Soccer, with general manager Paul McDonough describing him as a "well-versed" player who he expected to "make an impact right away".