He began his career with Racing Club and Estudiantes before joining River Plate in 2012, going on to win six domestic and international tournaments including the 2015 Copa Libertadores. In 2016, he joined Sevilla for €2.5 million.
Born in Puerto Madryn, Chubut, Mercado made his professional debut for Racing 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 joined Estudiantes 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 side Sevilla 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 manager Jorge Sampaoli to replace former captain Coke.[4]
He scored his first goal for the team on 20 September, deflecting Samir Nasri's free kick for the only score in a home Seville derby win over Real Betis.[5]
Al-Rayyan
On 11 June 2019, Al-Rayyan SC announced via their social media that they had signed Mercado.[6]
Internacional
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 the Argentina national team after being called up to join Diego Maradona's squad of Argentina-based players who beat Jamaica 2–1 on 10 February 2010.
In May 2018, Mercado was named in Argentina's preliminary 35-man squad for the 2018 FIFA World Cup in Russia;[8] later that month, he was included in Jorge Sampaoli's final 23-man squad for the tournament.[9] In the round of 16 match against France on 30 June, Mercado scored in a 4–3 defeat, which saw Argentina eliminated from the competition.[10]