Serie A's top marksman Edinson Cavani failed to score for the fourth league game in a row as fading Napoli lost further ground on leaders Juventus with a goalless draw at Udinese.
Napoli's third draw in succession meant they were left six points behind Juventus, who easily beat Siena 3-0 on Sunday.
Walter Mazzarri's side have mustered only one goal in those three games, a run which has coincided with a drought for Uruguay forward Cavani who had averaged over a goal a game in all competitions until the end of January.
Cavani remains stuck on 18 goals.
Second-placed Napoli have 52 points from 26 games and host Juventus on Friday evening in what could be their last chance to keep the title race alive.
Cavani missed an early chance when he just failed to connect with Giandomenico Mesto's cross at the near post while Marek Hamsik wasted the best first-half opening when he headed straight at goalkeeper Daniele Padelli.
The best second-half chance fell to Cavani but he poked the ball wide from six metres under pressure after Pablo Armero had broken down the left.
Mazzarri said he was heartened by his side's performance.
"I get annoyed when things go badly, but today I congratulated the lads because they did well," he said. "We created a lot of openings."
"Cavani played well today but there are moments when it doesn't work out for you."