Napoli was held to a scoreless draw by Udinese in Serie A on Monday, making it five straight games in all competitions without a win.
Meanwhile, two stunning long-range strikes helped Lazio beat Pescara 2-0 to pass both Milan clubs to move into third place, four points behind Napoli.
Chances were few and far between in Udine with both sides having only one shot on target all night.
Napoli started with an attacking line-up and went closest in the opening period when Marek Hamsik headed straight at goalkeeper Daniele Padelli just before halftime.
Edinson Cavani, the league's leading scorer, was guilty of a glaring miss when he failed to put away Pablo Armero's cross from six yards out.
Second-place Napoli is now six points behind defending champion Juventus, which it hosts on Friday.
Napoli has only scored one goal in the past five matches in all competitions.
"I think that if Napoli plays like we did tonight we can also put Juventus in difficulty," Napoli coach Walter Mazzarri said. "I have to give credit to my players. Today we played a great match against a tough opponent. We were just unlucky. However, when my team plays like that I am happy, I cannot complain. We created a lot of chances, but the ball just didn't drop for us."
In Rome, Lazio took the lead in the 29th minute when Senad Lulic cut the ball back to Stefan Radu, who hit a screamer into the top left corner from 25 yards. It was Radu's first Serie A goal after 119 games.
Lulic doubled Lazio's lead six minutes later with a brilliant solo goal, lashing another 25-yard thunderbolt into the top left corner.
It is Lazio's first win in six matches.
"We played a great first half today," Lulic said. "The three points are important.
"I am happy with my goal, but the most important thing is the victory. Now we have to prepare for the match against AC Milan."
Pescara is 19th in the table and five points off safety.