 On 15 December 2007 he appeared in his first game as a professional, starting in a 1–3 away loss against Polideportivo Ejido for the Segunda División championship.On 31 January 2008, Castellano moved to another reserve team, RCD Mallorca B also in the fourth level.He first appeared with the main squad on 8 January of the following year, coming on as a late substitute in a 3–1 home win over UD Almería for the Copa del Rey; eight days later, he was loaned to Segunda División B club Deportivo Alavés until June.