Zárate immediately endeared himself to the Lazio faithful, scoring twice in his Serie A debut against Cagliari and dedicating the second to the Lazio supporters. He also scored on his home debut, with a left-footed strike from outside the penalty area against Sampdoria. This rich goalscoring form continued with Zárate scoring once against Milan at the San Siro, twice against Torino and another against Siena. However, by mid-season, Zárate hit a dip in form and found himself being substituted for captain Tommaso Rocchi, who was returning to form following serious injury.