He began his career with Racing Club and Estudiantes before joiningRiver Plate in 2012, going on to win six domestic and international tournaments including the2015 Copa Libertadores. In 2016, he joined Sevilla for €2.5 million.
Born inPuerto Madryn,Chubut, Mercado made his professional debut forRacing Club on 21 February 2007 in a 0–1 home defeat to San Lorenzo. He went to establish himself as a regular member of the Racing first team.
In July 2010, Mercado joinedEstudiantes de La Plata for $800,000 and 50% of his rights.[3] He won the Apertura in his debut season, and stayed at the club until 2012.
On 4 August 2016,La Liga sideSevilla FC signed Mercado from River Plate on a three-year deal for a reported fee of €2.5 million, with River retaining 20% of a subsequent transfer fee. He was signed by compatriot managerJorge Sampaoli to replace former captainCoke.[4]
He scored his first goal for the team on 20 September, deflectingSamir Nasri's free kick for the only score in a homeSeville derby win overReal Betis.[5]
On 5 July 2021, he was announced and signed with Internacional until December 2022 after being without a club at the end of his contract with Al-Rayyan. His chosen jersey number was jersey number 25.[7]
Mercado made his full international debut for theArgentina national team after being called up to joinDiego Maradona's squad of Argentina-based players who beatJamaica 2–1 on 10 February 2010.
In May 2018, Mercado was named in Argentina's preliminary 35-mansquad for the2018 FIFA World Cup in Russia;[8] later that month, he was included inJorge Sampaoli's final 23-man squad for the tournament.[9] In the round of 16 match againstFrance on 30 June, Mercado scored in a 4–3 defeat, which saw Argentina eliminated from the competition.[10]