Lorenzo Insigne rescued a late point as Napoli now trail league leaders Juventus by 19 points after a frustrating 1-1 stalemate at Sassuolo on Sunday, as Serie A rivals Inter warmed up for next weekend's derby against Milan with a 2-0 win at home to SPAL.
Insigne netted the equaliser four minutes from time after Domenico Berardi had opened the scoring for midtable Sassuolo on 52 minutes in Modena.
Carlo Ancelotti's side's hopes of a first league title since 1990 have faded as Juventus continued their charge towards an eighth consecutive Scudetto with a 4-1 win over Udinese on Friday.
Napoli are far behind in second, six points ahead of Milan, who beat bottom club Chievo 2-1 on Saturday for a fifth league win in a row.
Inter are a further point behind in fourth.
Matteo Politano and Roberto Gagliardini scored in the second half as Inter shook off pre-derby tensions to beat SPAL 2-0 to revive their Champions League chase.
Carlo Ancelotti's side had taken just a point from their last two games, falling at Cagliari last time out, and desperately needed a morale-boosting win to keep pace with Milan before next week's Derby della Madonnina.
Argentina star Mauro Icardi was not present in the San Siro, remaining sidelined since being stripped of the captaincy a month ago amid a contract dispute.
The 26-year-old also remains uncertain for Thursday's Europa League game against Eintracht Frankfurt and Sunday's derby, both at the San Siro.
"I won't talk about Icardi," said coach Luciano Spalletti.
"Whatever I say gets translated into something else. I'm talking about the great goal by Politano, a great goal by Gagliardini, a great game by Lautaro.
"We should have done better at the start of the game, but we allowed the tension to choke us, and then became timid and insecure, but we're Inter and we had to win this game.
"We have this fire within us, but every now and then it becomes a flicker.
"Once the goal went in, everyone was totally transformed and brimming with confidence."
Quagliarella goes top
Spalletti's side had been frustrated in the first half by SPAL who are just two points above the relegation zone.
Lautaro Martinez looked to have given Inter the lead after half an hour on front of 61,000 fans in the San Siro but a VAR review awarded handball.
The hosts also lost Croatian midfielder Marcelo Brozovic, who limped off, with Joao Miranda also exiting at the break with a suspected broken nose.
Politano finally broke through after 68 minutes with Gagliardini turning in a Cedric assist nine minutes later.
The race for Champions League football remains tight with Roma, Torino and Atalanta six points behind fourth-placed Inter.
Torino continued their impressive form with Andrea Belotti claiming a double to extend their winning run to three games with a 2-1 win at Frosinone.
Walter Mazzarri's side move sixth and into the Europa League places, level on 44 points with Roma, who play at Empoli on Monday under new coach Claudio Ranieri, and Atalanta who beat Sampdoria 2-1.
Colombian Duvan Zapata broke through for the Bergamo outfit on 50 minutes and Robin Gosens scored the winner after 77 minutes.
Fabio Quagliarella had equalised for Sampdoria from the spot on 67 minutes as the 36-year-old went top of the Serie A goal-scoring charts with 20 in 27 games, one more than Juve star Cristiano Ronaldo.
Bologna earned a valuable three points with a 2-0 win over relegation rivals Cagliari.
Erick Pulgar and Roberto Soriano netted to give Bologna just their fourth win of the season as they remain third from bottom with Cagliari just six points clear of safety.