Текнико Университарио
On 11 August 2012, Mercado played his first match as a professional, coming on as a second-half substitute in a 0–0 away draw against Técnico Universitario, for the Ecuadorian Serie A championship. He scored his first professional goal on 12 May of the following year, netting his side's only in a 1–1 home draw against LDU Loja.