 After helping Atalanta back to the top Italian division, Zenoni made his Serie A debut with Atalanta on 1 October 2000, against S.S. Lazio, and along with his brother, Cristian, established himself as one of the most promising young full-backs in the league throughout the 2000–01 season.In 2005, he joined Udinese under the Bosman ruling, leaving Atalanta 5 months before his contract had ended.He signed a 4 year-deal which would keep him at his new club until 2009.