Napoli moved back into title contention with a 1-0 win at Cagliari on Monday, placing the southern club two points behind Italian league leader Juventus.
With Napoli's leading scorer Edinson Cavani suspended and fellow forward Goran Pandev out injured, Marek Hamsik found the target in the 72nd minute with an angled shot from inside the area to finish off an action began by Lorenzo Insigne, who also hit the post in the first half.
Meanwhile, Inter Milan wasted a chance to move within one point of the lead with a 1-0 loss at Parma, where Nicola Sansone put the hosts in front with an impressive solo action in the 75th.
Inter sorely missed the creativity of Antonio Cassano, who is serving a two-match ban for insulting the referee. Inter manager Andrea Stramaccioni was also banned.
Juventus, which lost 1-0 to AC Milan on Sunday, leads with 32 points. Napoli is next with 30 and Fiorentina and Inter have 28 each, leaving four clubs within four points of each other at the top of the table.
Napoli is attempting to win Serie A for the first time since Diego Maradona led the club to titles in 1987 and 1990.
"We're nine points ahead compared to last season and we've advanced in the Europa League with a match to spare. I can't ask for anything more from these guys," Napoli coach Walter Mazzarri said. "Tonight, too, despite the absences, we had a great performance. ... We really showed our maturity, but we're going to continue taking it game by game."
Parma is seventh and Cagliari is tied for 11th.