[6] Formed at River Plate, he spent most of his career in Italy, making 215 Serie A appearances and scoring 46 goals for Catania, AC Milan, Sampdoria, Chievo, Torino and Udinese.

He also played in Spain for Barcelona and Mallorca, winning the La Liga and UEFA Champions League double with the former in 2006, and for Grêmio and Vasco da Gama in the Campeonato Brasileiro Série A. López began his career in 1997 with River Plate.

[7] On his UEFA Champions League debut on 23 February, he came on as a second-half substitute for Ludovic Giuly and within four minutes beat Chelsea defender William Gallas to score an equaliser with his first shot for the club, an eventual 2–1 first-leg win.

[9] López failed to break into the club's first team; in his two seasons in La Liga, he made just 14 league appearances.

[10] He scored 3 goals in 25 matches, and returned to Barcelona in the summer of 2007, only to be sold to FC Moscow on 16 August 2007 after a €2 million transfer fee was agreed by the clubs.

[18] On 18 December 2011, in the match won 2–0 by Catania against Palermo, he converted his second penalty of the season and was tearfully substituted by Gonzalo Bergessio for a possible farewell before the winter session of the transfer window.

[23] On 30 June 2014, López signed a one-year deal with Chievo with an option to extend his contract for a further year after Catania relegation.

[24] He made his debut on the first day of the 2014–15 Serie A season, 30 August, against Juventus, playing the full 90 minutes of a 1–0 home loss.

[30] On 14 July 2018, López joined Vasco da Gama, signing an eighteen-month contract with an option for another year.

[32] López represented his birth nation of Argentina at under-15, under-17 and under-20 levels, also taking part to the 2003 South American Youth Championship.

[34] During the April 2014 Serie A match between Sampdoria and Inter, López notably refused to shake Icardi's hand, leading the press to dub the game the "Wanda derby".

[35] López's change of luck from being a somewhat criticised forward at River Plate to being signed by Barcelona made him an internet meme in his native Argentina.

After Argentina's elimination from the World Cup, without López in the 23-man squad, the nature of the meme changed to a series of reasons explaining his lack of time play on Barcelona with hyperbolic claims which closely resembled Chuck Norris Facts.

[36] López and fashion industry businessman Paul Richardson led a consortium interested in buying English Championship club Birmingham City.