Ezequiel Lavezzi's second-half strike gave Napoli a 1-0 win over struggling Inter Milan which piled the pressure on Nerazzurri coach Claudio Ranieri after a seventh defeat in eight matches.
The Argentine striker scored the only goal at the San Paolo with an angled drive on 59 minutes to lift Napoli to 40 points and fifth place.
Inter, who remain in seventh on 36 points, nine off the Champions League qualifying places, even enjoyed a one-man advantage for the final 12 minutes after Salvatore Aronica's sending off.
But their dismal record of not having won a Serie A match in Naples since 1997 continued.
Ranieri insisted his job was safe.
"I don't know what the president (Massimo Moratti) will do now. This is a question for him. I would say Ranieri should continue. I still believe in these players," said the coach.
Napoli coach Walter Mazzarri praised his team.
"I'm in love with these guys. It's two years that we've been together and they've grown immensely. This is our fifth game without conceding," he said.
Goals from Antonio Di Natale - his 18th of the campaign - Dusan Basta and Antonio Floro Flores saw Udinese win 3-1 at Bologna to stay third, while a 36th-minute goal from Miroslav Klose - his 13th of the season - saw Edy Reja's Lazio get back to winning ways with a 1-0 win over Fiorentina.
Udinese and Lazio move to 45 points, five points behind second placed Juventus who remain a point behind AC Milan with a game in hand after Saturday's 1-1 draw at the San Siro.
Napoli continued where they left off in the Champions League against Chelsea on Tuesday with Swiss midfielder Blerim Dzemaili, starting for the suspended Marek Hamsik, forcing Julio Cesar into a flying save with a fierce strike on 25 minutes.
Playing in front of another near full house, Uruguayan striker Edinson Cavani flashed a header agonisingly wide three minutes later after the on-form Lavezzi had won a free kick with a dazzling run.
Inter came within a whisker of taking the lead two minutes before the break when Dutch playmaker Wesley Sneijder bent a trademark free kick just off target.
Sneijder and Uruguayan forward Diego Forlan were replaced at half-time by Giampaolo Pazzini and Ivan Cordoba but Inter were breached on 59 minutes as Lavezzi picked up Dzemaili's pass before drilling the ball low into the corner.
Brazilian goalkeeper Cesar came to the Nerazzurri's rescue twice in as many minutes, saving bravely from Cavani on 63 minutes before turning aside another Dzemaili strike as Napoli searched for the killer second.
Aronica was given his marching orders for hauling down Pazzini but the Italian striker nodded a gilt-edged chance wide at the death.
Roma's bid for a top-three finish received another setback when they fell to a heavy 4-1 defeat at Atalanta.
The loss - Roma's third in their last four away games - leaves Luis Enrique's side in sixth place.
Roma were without two of their talismen, with Francesco Totti suspended and Daniele De Rossi left out of the match-day squad by Enrique.
The decision to exclude De Rossi was not appreciated by the travelling Roma fans and in his absence, Atalanta's Argentine striker German Denis claimed a hat-trick that took his tally for the season to 15 league goals.
Saturday's 1-1 draw between top two AC Milan and Juventus was overshadowed by controversy surrounding a Sulley Muntari header for Milan that was not given despite the ball having clearly crossed the line.
With Antonio Nocerino having opened the scoring for Milan through a deflected 14th-minute shot, Muntari's effort 11 minutes later would have doubled their lead if it had been awarded.
As it was, Juve equalised through Alessandro Matri in the 83rd minute to leave Antonio Conte's men a point behind defending champions Milan in second place but with a game in hand, at Bologna on March 7.