Born in Argentina, Mariano Messera is a midfield marshall who began his career with Gimnasia La Plata. Coming through the youth team, Mariano made his debut in 1997 and went onto play 160 league games scoring 36 goals for the side. In 2002, he was transferred to Cruz Azul, a Mexcian Primera Division side where he stayed for two seasons, returning to Argentina in 2004.
On his return, he joined Rosario Central for one season, scoring 5 goals, and then moved to Calcio Catania in the Italian Serie A, for a short period. He returned to San Lorenzo the following year, but in search of regular playing time, moved to O’Higgins in 2006. He played 14 games and scored 3 times at O’Higgins before moving to Skoda Xanthi, a greek football team. 22 games and 3 goals later, Messera was back in Rosario, playing for their big side, Rosario Central. At the end of the 2007-08 season, Messera was brought into Gimnasia La Plata.