Lautaro Martinez ensured that Inter Milan kept hold of their two-point lead at the top of Serie A as he struck in Sunday's scrappy 1-1 draw at closest rivals Juventus.
AC Milan starlet Francesco Camarda made history on Saturday after becoming the youngest ever player to play in Serie A during Saturday's 1-0 win over Fiorentina.
Mazzarri's team are still seven points behind leaders Inter Milan who travel to Turin on Sunday for the weekend's big match at second-placed Juventus
Inter Milan and Juventus face off on Sunday in a clash between Serie A's two title favourites and historic rivals, as Walter Mazzarri begins his second reign at troubled Napoli.
Napoli continued their struggles on home turf with Sunday's shock 1-0 defeat to Empoli which left the Serie A champions already well off the pace in this season's title race.
Napoli winger Matteo Politano and forward Giacomo Raspadori both scored after the break to cancel out two first-half headers by Olivier Giroud in an energetic game that saw the two teams dominate one half each.
Argentina striker Martinez nodded home his 11th league goal of the season in the 67th minute of a straightforward win in Turin as Inter went one point ahead of AC Milan, who host third-placed Juventus on Sunday night.
Italian club Juventus' midfielder Nicolo Fagioli is under investigation for alleged illegal betting activities, a prosecutor said on Wednesday, confirming earlier press reports.
Bologna fought back from two goals down to snatch a 2-2 draw with Inter Milan at the San Siro in Serie A on Saturday after early goals from Francesco Acerbi and captain Lautaro Martinez had put the hosts in command.