Cerci grew up playing football in Valmontone before joining the Roma youth system. At this time, he was nicknamed "l'Henry di Valmontone" ("the Thierry Henry of Valmontone") due to his playing style. On 16 May 2004, he made his debut in Serie A at the age of 16 under Fabio Capello in the 76th minute against Sampdoria, ending 0–0. The following season, he was a key player in the Roma under-19 side that won the Campionato Primavera 2004–05. With the first team, he made an additional two appearances, playing the final minutes against Internazionale and Cagliari.