At Atalanta, Barreto missed most of his first season through injury, only returning in the last days of the season and not being able to avoid the relegation of his club in Serie B. His excellent performances in Serie B afforded the interest Napoli during the January market. He contributed to the promotion of the "Bergamaschi" to Serie A in the 2010–11 season, at the end of which he was voted into "Top 11 Serie B" players team by Italian journalists.