Juventus conceded their place in Serie A's Champions League positions on Wednesday after falling to a 1-0 defeat at Parma, one of four matches rescheduled from Monday following the death of Pope Francis.
Juventus, who are just a point below fourth-placed Bologna, visit Roma on Sunday.
Thiago Motta was sacked as Juventus coach on Sunday after less than one season in charge with former player Igor Tudor replacing him, the Italian giants announced.
Francisco Conceicao made sure that Napoli would stay two points ahead of reigning champions Inter by classily tucking home the winning goal 16 minutes before the end of an entertaining contest in Turin.
Inter Milan could be without French forward Marcus Thuram due to an injury as they prepare for a tough outing against Juventus at the Allianz Stadium on Sunday, manager Simone Inzaghi said on the eve of the Serie A clash.
Samuel Mbangula boosted Juventus' chances of reaching the last 16 of the Champions League by netting the late winner in Tuesday's 2-1 success over PSV Eindhoven in Turin.
The victory, provisionally, leaves Juventus level on points with champions Inter Milan in second and one behind league leaders Napoli.
The record 36-time champions trail second-placed Inter Milan on goal difference after Maduka Okoye's own goal and Nicola Savona's effort.
Manager Thiago Motta acknowledged that Juventus are not in the Serie A title race just yet and emphasised the importance of maintaining focus on their growth after they secured a dramatic 4-4 draw with champions Inter Milan thanks to two late goals on Sunday.
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.
A stunning first-half brace by striker Dusan Vlahovic helped Juventus to a 3-0 win over Sassuolo in Serie A on Tuesday as Massimiliano Allegri's side extended their unbeaten league run to 15 games in front of a sold-out home crowd.
Adrien Rabiot's second-half goal earned Juventus a 1-0 home win over AS Roma on Saturday that took them within two points of Serie A leaders Inter Milan.
Yann Bissek's first goal in Italy just before half-time at the San Siro and a late finish from Nicolo Barella were enough for Inter to bounce back from cup defeat to Bologna midweek and keep closest challengers Juventus at bay.
Turkey playmaker Hakan Calhanoglu set up a goal and scored another as Inter Milan moved back to the summit of Serie A with Saturday's comfortable 4-0 home win over Udinese.
Inter Milan and Juventus face off on Sunday in a clash between Serie A's two title favourites and historic rivals, as Walter Mazzarri begins his second reign at troubled Napoli.
Italian club Juventus' midfielder Nicolo Fagioli is under investigation for alleged illegal betting activities, a prosecutor said on Wednesday, confirming earlier press reports.
The 30-year-old former Manchester United player, a World Cup winner in 2018, faces a ban of up to four years.
Lukaku grabbed his third goal in five league games for Roma after latching onto a clever pass from Paulo Dybala midway through the first half.
Leonardo Bonucci has confirmed that he is taking legal action against Juventus, claiming that the Serie A club has not told the truth about their treatment of him after he was frozen out and eventually sold over the summer.
