He successively joined the Nacional youth academy, where he turned into a very prolific striker and, more occasionally, left winger.

[2] On 24 April 2011, after being born as part of the first team under head coach Juan Ramón Carrasco, López made his debut at the age of 17 in a league game against Central Español, promptly scoring also his first senior goal.

López was acquired by Roma in the January 2012 transfer window, and then included in the Primavera under-19 squad for the rest of the season, scoring 15 times in 12 youth games.

López was taken into consideration as a first team player by new head coach Zdeněk Zeman, who included him in the senior roster for the pre-season camp and then featured him in a number of friendly games.

López made his first team debut on 26 August 2012, replacing captain Francesco Totti in the final minutes of the first game of the Serie A season, a home match versus Catania, and promptly scored an injury time equaliser (the game ended 2–2).