Roa started playing professionally for Racing Club de Avellaneda, making his Primera División debut on 6 November 1988, aged 19. During a summer tour of Africa with the club, he contracted malaria, but fully recovered. In 1994, he moved to Club Atlético Lanús, rarely missing a match with the Buenos Aires Province side as it achieved three consecutive third-place league finishes (one in 1995, two in 1996), and adding the Copa CONMEBOL in 1996.