Reigning champions Inter came through what was supposed to be a tough test at the Stadio Olimpico with flying colours and are three points off the Scudetto pace with a game in hand.
Substitute Zaniolo decided a hard-fought encounter in Sardinia by stroking home Raoul Bellanova's cut-back in the 66th minute and moving Atalanta five points clear.
Edoardo Bove has had a defibrillator fitted after the Fiorentina midfielder's on-pitch cardiac arrest earlier this month, according to widespread Italian media reports on Tuesday.
Fiorentina earlier remained on Napoli's heels after their 1-0 home win over Cagliari in their first league match since midfielder Edoardo Bove's sudden collapse last weekend.
Edoardo Bove is conscious and alert in hospital after his sudden collapse which caused Fiorentina's match with Inter Milan to be called off, the Serie A club said on Monday.
Fiorentina's Serie A match with Inter Milan was stopped on Sunday after midfielder Edoardo Bove suddenly collapsed to the ground.
"It's too early to talk about the title. All we can do is look out for how we develop as a team, work to improve and win every match we play. But now is not the moment to talk about the title," said Lukaku.
Juventus remain the only unbeaten side in Serie A but their seventh draw of the season means they remain sixth in the standings and are now three points behind leaders Inter Milan. Milan stay seventh, six points behind Juve, though they have played one game fewer.
Simone Inzaghi's side are provisionally ahead of Napoli after netting all five of their goals in the opening 45 minutes at the Stadio Bentegodi through a Marcus Thuram brace and further strikes from Joaquin Correa, Stefan de Vrij and Yann Bisseck.
Inter Milan cruised to a 4-0 home win against Atalanta in Serie A on Wednesday, extending their lead at the top of the standings to 12 points as they edge closer to a 20th league title.
"The talent of the champion came out. Players like Paulo are decisive and for me they should never be questioned," said Roma coach Daniele De Rossi.
Argentina striker Martinez joined the 100 club in Italy's top flight when he opened the scoring in the 15th minute in southern Italy.
Inter Milan stretched their lead at the top of Serie A to 10 points on Friday after cruising past sorry Salernitana 4-0 ahead of their Champions League clash with Atletico Madrid.
Juve's title hopes took a hit at the Allianz Stadium in Turin after Lautaro Giannetti poked home the only goal of the game in the 25th minute.
Marcus Thuram was key to Inter's win at a soaking Stadio Olimpico in Rome as, with his team trailing at half-time, the France attacker made it two goals each shortly after the break and forced the Angelino own goal which put Inter ahead in the 56th minute.
Ideally, sports and politics should never mix, but inevitably, sports and politics always mix.
Paulo Dybala scored twice as Roma eased to a 4-0 thumping of Cagliari at the Stadio Olimpico on Monday to notch a third straight Serie A win under Daniele De Rossi.
Simone Inzaghi's side prevailed in a tense but eventful clash at the San Siro thanks to Federico Gatti's own goal eight minutes before half-time
The Serie A title credentials of Inter Milan and Juventus will be on the line on Sunday as two giants of Italian football face off in a San Siro showdown.
