ナウチコ
Born in Ijuí, Rio Grande do Sul, Mattioni joined Grêmio Foot-Ball Porto Alegrense in 2004, being promoted to the main squad three years later but failing to appear in the Série A in his first season. However, after performing well in the Campeonato Brasileiro Sub-20 and appearing in the Campeonato Gaúcho, he made his debut in the top division in a 2–0 home win against Clube Náutico Capibaribe.