On 9 July 2013, Sassuolo, recently promoted to the Serie A, purchased half of Acerbi's playing rights for a €1.8 million fee. another remained a propriety of Genoa. During a pre-season medical, unusual blood tests revealed a testicular tumour, having surgery to remove the tumour. Soon after having the tumour removed, he resumed training with his new teammates. Acerbi had taken part in 13 games of the 2013–14 Serie A season before he failed a doping test in December 2013; he denied using any banned performance-enhancing drugs, and that it was due to irregular hormone levels caused by the return of the cancer. He subsequently underwent chemotherapy from 7 January to 14 March 2014. It was also reported that Acerbi did not miss the majority of training sessions during his cancer treatment period. Despite this, his return to the pitch was postponed until the next season.