Leaders Napoli were held to a goalless home draw by relegation-threatened Hellas Verona in Serie A on Saturday as Luciano Spalletti's side finished winless for the third time in their last four games in all competitions.
Napoli thought they had opened the scoring in the 20th minute but Matteo Politano's deflected strike was disallowed after Verona goalkeeper Lorenzo Montipo was obstructed by a player in an offside position.
The visitors had a chance to take a surprise lead just before the half-hour mark but striker Kevin Lasagna, who ended a solo run with a powerful shot from a distance, was denied by Napoli keeper Alex Meret.
Although Napoli enjoyed the lion's share of possession, reaching 81 per cent in the second half, they appeared toothless against Verona's solid defence and managed only three shots in the opening 45 minutes, none of them on target.
Substitute Victor Osimhen, returning from being sidelined due to a thigh strain, wasted a promising chance in the closing stages when he hit the bar in the 82nd minute.
Verona could have sealed a win in stoppage time through a solo effort by winger Cyril Ngonge who, one-on-one with Meret, struck well wide of the target.
Napoli's advantage over second-placed Lazio narrowed to 13 points after Maurizio Sarri's men grabbed a comfortable 3-0 win at lowly Spezia on Friday.
Verona, 18th on 23 points, are three points from safety.