Monaco recovered from Zlatan Ibrahimovic's early goal to draw 1-1 with Laurent Blanc's men on Sunday and will go into Wednesday's clash with Bastia as league leaders.
It is quite an achievement in their first season back in the top flight, even considering their immense financial investment, and has led many observers to view this season's league as a straight fight between the big-spending pair.
But Ranieri said: "It's too early to say. We have to wait until the middle of the season.
"(Blanc) is a good friend, a good coach, but I hope that at the end of the season Monaco are ahead of PSG."
Blanc takes his side, apart from thigh injury victim Thiago Silva, to Valenciennes earlier on Wednesday evening while the other early-season pace-setters, Marseille and St Etienne, meet at the Stade Velodrome on Tuesday.
Both teams have injury troubles, with Andre-Pierre Gignac (toe) and Jeremy Morel (knee) absent for OM. Dimitri Payet, though, could feature after back pain forced him to miss the goalless draw with Bastia.
For Les Verts, striker Brandao will miss the reunion with his former club due to a thigh problem while Loic Perrin is also absent with a calf injury.
There was also bad news on the injury front for Lyon, who are likely to be without Mouhamadou Dabo (hamstring) at Ajaccio, and Bordeaux who host Reims knowing midfielder Andre Poko will be missing for between six weeks and two months due to a broken foot.
Lille bounced back from defeat to Nice by beating Sochaux 2-0 on Saturday with a brace from Nolan Roux and midfielder Marvin Martin wants to see his eighth-placed team continue their resurgence against Evian on Tuesday.
Martin told the club's website: "The team is progressing every game, whether in terms of our aggression or our style of play. We must continue in this direction and not do anything silly."
The remaining Wednesday games see Guingamp host Sochaux, Nice travel to Nantes and Toulouse take on Lorient, while Montpellier face Rennes on Thursday.