The Giallorossi are currently fourth in the table on 19 points, with the away side one point further back in sixth, behind Roma's big rivals Lazio on goal difference.
Fonseca's side have lost just once in the league this season and despite their ongoing midfield injury crisis, they are consistently finding a way to keep games tight and force opportunities.
Interestingly, none of the last six meetings between these sides has been won by the home side.
Napoli had a tougher time of it in the week, being held to a 2-2 draw by Atalanta despite taking the lead on two occasions.
One bright spark from that game was Arkadiusz Milik, who grabbed his fourth of the season and looks to be finding his best form again after his recent injury troubles.
Carlo Ancelotti's side have been good themselves at set pieces this year but they have also been too open defensively and too easy to create chances against, something that will be a boon to Roma's talented attacking players.
Napoli will be without their manager for this game though, after he was sent off on Wednesday evening.
Saturday's game is likely to be a high tempo affair given the desire of both sides to play possession football, although Napoli are likely to have the lion's share in this game given Roma's well-publicised injury issues.
Roma recent form: LWDDWW
Roma recent form (all competitions): DDDDWW
Napoli recent form: LWDWDD
Napoli recent form (all competitions): DDWWDD
Roma are set to be without as many as eight first team players for Saturday's game, meaning that Fonseca will once again have to be very careful with how he sets his team out.
Ancelotti is likely to make some changes to his side, with one eye on their Champions League home tie against Red Bull Salzburg on Tuesday evening.
Roma possible starting lineup:
Lopez; Santon, Smalling, Cetin, Kolarov; Veretout, Mancini; Zaniolo, Pastore, Kluivert; Dzeko
Napoli possible starting lineup:
Meret; Di Lorenzo, Koulibaly, Maksimovic, Rui; Callejon, Zielinski, Ruiz, Lozano; Milik, Mertens
We say: Roma 2-2 Napoli
On paper these two sides are very evenly matched and that is likely to play out on Saturday, with the home side probably doing enough to secure a point.