 He was a favorite of interim coach Carlos Bilardo, and together with Marcelo Carrusca started helping the team improve their standing in the Argentine league.The highlight of his tenure with Estudiantes was being a key piece in the 7–0 defeat of derby rivals Gimnasia on 15 October 2006, and then his role in helping the team win their first league title since 1983 by scoring the equalizing goal from a free kick against Boca Juniors in the 2006 Apertura final playoff game.On 24 February 2007, a deal was announced between Estudiantes and Bayern Munich, in which Sosa would be transferred to Bayern Munich for an undisclosed fee.