Hamšík started in the 2012 Supercoppa Italiana, held in Beijing, on 11 August; however, Napoli were defeated by Juventus 4–2 in extra time. Later that month, in Napoli's first league fixture of the 2012–13 Serie A season, Hamšík scored the club's first goal and assisted Christian Maggio's strike in an eventual 3–0 defeat of Palermo. Missing leading goal-scorer Edinson Cavani for the club's match against Chievo on 28 October 2012, Hamšík connected on a Juan Camilo Zúñiga cross to give Napoli a 1–0 victory. On 6 January 2013, he made his 200th Serie A appearance in a 4–1 home win over Roma. On the penultimate matchday of the Serie A season, Hamšík collected a pass from Goran Pandev and nudged the ball home in the 93rd minute, rescuing a 2–1 win over Siena, confirming the club's place in the group stages of the Champions League while condemning Siena to relegation. The Slovak featured in every Serie A match for Napoli during the 2012–13 season, providing 11 goals and 14 assists as the "Partenopei" finished second behind reigning champions Juventus, a season which proved to be manager Walter Mazzarri's last at the club, as he became coach of Internazionale later that summer.