[2] On 24 October 2017, before even appearing with the reserves, he made his professional debut by coming on as a second-half substitute for Chuli in a 1–0 home loss against Deportivo Alavés, for the season's Copa del Rey.
[9] He made his first-team debut for Los Blancos on 20 February, in a 1–0 away win over Real Valladolid,[10] and he first appeared in the UEFA Champions League four days later, as he replaced Marco Asensio in a 1–0 victory over Atalanta B.C.
[12] On 31 August 2021, Duro moved to fellow first division side Valencia CF on a one-year loan deal, reuniting with former Getafe manager José Bordalás.
[17] In the 2021–22 Copa del Rey, Duro scored the winner in a 2–1 quarter-final win against Cádiz CF on 2 February 2022,[18] and the equaliser in the first leg of the semi-final against Athletic Bilbao eight days later.
[19] In the final on 23 April, he netted Valencia's goal in the 1–1 draw, being replaced by Bryan Gil with five minutes of regulation time remaining in an eventual penalty shootout defeat to Real Betis.