Answer by taking a quote from the following article:

Juan Sebastian Veron (Spanish pronunciation: ['xwan sebas'tjam be'ron]; born 9 March 1975) is a retired Argentine footballer who as the chairman for Estudiantes de La Plata, where he had served as Director of Sports. A former midfielder, Veron's career started in Estudiantes, continued in Argentina's Boca Juniors, and included stints in several clubs in the Italian Serie A (where he won the Scudetto with Lazio and with Internazionale, and a UEFA Cup with Parma), and England's Manchester United and Chelsea. In 2006, Veron returned to Estudiantes, where he remained until his retirement in 2014, aside from a brief spell with Brandsen. He has announced his short return to first team will occur in Copa Libertadores 2017.

Veron was called up for the 1998 FIFA World Cup in France, where Argentina was eliminated by the Netherlands in the quarter-finals. A rumour (never confirmed) that Veron had failed an internal doping test, and allegations of laziness hampered his relationship with the media and fans. He was called up again for the 2002 World Cup in Korea/Japan, where Veron was regarded as a key player and captained the side in place of the injured Roberto Ayala. Some fans held him personally responsible for Argentina's dismal performance, which included a loss to England and elimination in the group phase.  After then-national coach Jose Pekerman omitted him from the 2006 World Cup squad, his replacement, Alfio Basile recalled Veron to the national squad in February 2007, based on his performance in Estudiantes's 2006 championship team. Veron was a starter in the Argentine team that reached the final of Copa America 2007. Due to injuries and Estudiantes's busy schedule, Veron did not feature in the immediate plans of national coach Diego Maradona, but was recalled to the Argentine squad as a second-half substitute in the 4-0 win over Venezuela on 28 March 2009, Maradona's first competitive game in charge of the national team. He also played in the starting XI in a 2010 FIFA World Cup qualifier against Colombia on 6 June 2009 and was selected by manager Diego Maradona in the final 23-man squad for the finals of the 2010 FIFA World Cup.  Veron started Argentina's first group match against Nigeria, and provided the assist for Gabriel Heinze's goal. After missing the match against South Korea due to injury, Veron returned to the starting line-up against Greece and played the full 90 minutes as Argentina won 2-0. He came on as a substitute for Carlos Tevez in the 69th minute in Argentina's 3-1 victory over Mexico in the Round of 16, but did not feature during the quarterfinal loss to Germany.  On 26 August 2010, Veron retired from international football. Nevertheless, Veron appeared again for Argentina in the 2011 Superclasico de las Americas, a two legged, non-FIFA sanctioned exhibition, between Argentina and Brazil's domestically-based players.

How did that effect his career?
After then-national coach Jose Pekerman omitted him from the 2006 World Cup