returned to River Plate for the club's pre-season training, stating that he would sign with the club only if he could deal with the physical demand after having undergone surgeries to his heel and not having played since leaving Johor Darul Ta’zim in April 2014. On 31 May, he played as substitute in a home win against Rosario Central in the Primera División. Aimar announced his retirement on 14 July 2015 after River Plate coach Marcelo Gallardo informed him that he was not included in the club's squad for the semi-final stage of the Copa Libertadores. Gallardo said Aimar was "suffering" and had struggled with injuries through the pre-season. Estudiantes de Río Cuarto On 16 January 2018, Aimar played in a friendly match for his youth club Estudiantes de Río Cuarto. After the match, he announced that he would be joining the squad ahead of the Copa Argentina fixture against Sportivo Belgrano on 23 January, in order to fulfill his wish of making an official appearance for the club where he began and spent eight years. The Copa Argentina match took place at Estudiantes' home stadium Estadio Ciudad de Río Cuarto. Aimar was picked in the starting line up and wore the captain's armband, coming close to opening the score with a shot that was parried by the goalkeeper, before getting subbed off in the 50th minute. The match ended in a goalless draw, which was not enough to see Estudiantes through the next round after a 2–1 loss in the first leg. His brother Andrés was also in the line-up of Estudiantes. Afterwards, Aimar confirmed that he had no intention of making a definitive comeback and that this was indeed his farewell match from football. International career Aimar first represented Argentina at youth levels. Along with future senior team players Esteban Cambiasso and Juan Román Riquelme he won the 1997 FIFA World Youth Championship and went on to earn 52 senior caps following his debut in 1999, scoring eight international goals in total. He represented Argentina at the 1999 and 2007 editions of the Copa América, at the 2002 and 2006 FIFA World Cups, and at the 2005 FIFA Confederations Cup. In the 2002 World Cup, for which he was picked ahead of Riquelme, Aimar appeared against England, subbing in for Juan Sebastián Verón in the 1–0 loss, which led coach Marcelo Bielsa to start him against Sweden at