On 8 August 2013, one month shy of his 18th birthday, Cotán made his first official appearance with the Andalusians, playing the entire second half in a 6–1 away win over FK Mladost Podgorica in the third qualifying round of the UEFA Europa League. On 11 May of the following year, as the main squad had already secured the fifth place and manager Unai Emery was resting his starters for the Europa League final, he made his La Liga debut, featuring the full 90 minutes in a 0–1 loss at Getafe CF.