Mérida was called up to the Spanish under-20 team for the 2009 World Cup held in Egypt: he starred in an 8–0 drubbing of Tahiti, scoring the fifth goal and providing an assist. In the next group game he continued his fine form and netted twice in a 2–0 win over Nigeria; after resting in the third group game against Venezuela (3–0) he played 76 minutes in the last-16 tie against Italy, which finished with a 1–3 loss.