On 22 July 2011, Heinze joined Serie A side A.S. Roma after being released by Marseille at the end of June. He made his competitive debut on 11 September, in a 1–2 home loss against Cagliari. On 19 March 2012, after appearing in his 25th official game, Heinze had his contract automatically renewed for another year. However, just five months later, it was announced on Roma's official website that he was being released from his contract with immediate effect; the day after his release he joined his original club, Newell's Old Boys, on a two-year deal. Heinze first represented Argentina on 30 April 2003, in a friendly away win with Libya. The following year, he won a gold medal in the 2004 Summer Olympics in Athens, scoring in a 6–0 group stage rout of Serbia and Montenegro. Despite missing most of 2005–06 with Manchester United due to injury, Heinze was called up for the 2006 FIFA World Cup finals in Germany. In the quarter-final clash against the hosts, he started as Argentina lost on penalties. Heinze participated in the 2007 Copa América, scoring with his head from a Juan Román Riquelme free kick in the semi-finals against Mexico, a 3–0 win for the eventual runners-up. In the 2010 FIFA World Cup he played in four of Argentina's five matches in South Africa, netting the game's only goal – his third international – in a group stage victory over Nigeria. Even though he still did not possess the proper license, Heinze began working as a manager in June 2015, being appointed at Godoy Cruz in the Argentine Primera División. He was sacked on 27 September, following two wins, two draws and six defeats. In June 2016, Heinze signed at Argentinos Juniors also as a coach. In July of the following year, after achieving top-level promotion, he resigned. On 11 December 2017, in the same capacity, he was appointed at Vélez Sarsfield. Having led the club to two consecutive Copa Sudamericana qualifications, he chose not to continue past the end of the 2019–20 season. Heinze was named in the Panama Papers, a 2016 leak of offshore accounts used for tax evasion. In 2005, he signed an endorsement with Puma AG in which at least a million dollars was paid to him over a period of five years through an account in his mother's name in the British Virgin Islands.