In 2010 Delfino, was promoted to the Primera División referees crew, being his first game in the top tier of Argentinian football on 9 October 2010 when he took charge of a 1–1 draw between Huracán de Parque Patricios and All Boys.

He is part of the Asociación Argentina de Árbitros (in English: Argentine Referees Association), where he lost the 2013 Union Elections.

The second one, played on October at the Monumental, ended with a 1–0 to Boca Juniors, who won after a goal scored by Gigliotti in the first half.

One year later, Delfino officiated the 2015 Copa Libertadores Round of 16, between the two biggest teams of the country.

He took charge of the 2015 Recopa Sudamericana Final first leg, between San Lorenzo and River, with a 1–0 favour to the second team, who won with a Sánchez goal.