Napoli failed to fully exploit Serie A leaders Juventus' slip-up as the second-placed side were held 0-0 by Sampdoria on Sunday.
Champions Juve were beaten 1-0 away to Roma on Saturday, giving Walter Mazzarri's men a gilt-edged chance to close to within two points of the leaders with a win over 12th-placed Sampdoria.
But the Naples club couldn't find a way past Sampdoria goalkeeper Sergio Romero, as they were frustrated by a scoreless stalemate at the Stadio San Paolo.
A Marco Sau brace guided Cagliari to a 2-0 away win over Pescara at the Stadio Adriatico-Giovanni Cornacchia.
Sau improved his season tally in the Italian top flight to eight, while Pescara's plight to battle relegation was not helped by a late dismissal to midfielder Vladimir Weiss.
Pescara are now four points from safety in 18th spot.
Genoa was able to create that gap on Pescara as they wrapped up an upset 1-0 win at home to Udinese.
Juraj Kucka struck in the 33rd minute to help Davide Ballardini's men create some breathing space on the drop zone.
Catania climbed to seventh on the table with a 1-0 victory at home to Bologna, with Sergio Almiron scoring the game's only goal three minutes prior to the interval.
Torino scored late to earn a 2-1 win at home to Atalanta, with Valter Birsa's 87th-minute strike sealing all three points for Giampiero Ventura's men.
Alessio Cerci had put the Stadio Olimpico hosts ahead on 43 minutes, only for a penalty to be converted by German Davis to see Atalanta level with 15 minutes to play.
But Birsa popped up late, assisted by Matteo Darmian, to score the winner.