Rennes were missing the injured Martin Terrier and suspended Benjamin Bourigeaud, and in light of them losing two of their last three league matches, the hosts set up in an unfamiliar shape.
Bruno Genesio deployed a back three for the first time this season, hoping to nullify leaders PSG at Roazhon Park, and his men did so to the fullest extent in the opening skirmishes, with wayward strikes from Lionel Messi and Vitinha the best Les Parisiens could muster.
The hosts weren’t simply sitting back though, with an Arnaud Kalimuendo effort from Adrien Truffert’s cross forcing Gianluigi Donnarumma into a save, and offering a reminder of the threat Rennes pose when they foray forward.
Lovro Majer also tested the Italian with a free-kick after Kalimuendo’s running behind caused problems for his former club, and Donnarumma was once again called into action by Amine Gouiri following his darting run inside. At the other end, Joe Rodon was then on hand to make a block from Messi shortly before halftime.
With Christophe Galtier’s words likely still ringing in PSG ears, Danilo Pereira headed the visitors’ biggest opportunity of the match straight at Steve Mandanda mere minutes after the restart.
Les Parisiens’ boss then introduced Kylian Mbappe and Achraf Hakimi in the 55th minute, but Hakimi’s first major moment of the game was to be beaten by Truffert, who pulled the ball back for captain Hamari Traore to emphatically score his first of the season and give Rennes a fully-deserved lead.
Mbappe then squandered a fantastic opportunity to equalise, missing the target completely and setting Rennes’ nerves jangling.
A late goal was always a possibility, as no club has scored more Ligue 1 goals after the 75th minute than these two teams so far, but Mandanda tipped Juan Bernat’s late attempt over the crossbar, as Rennes secured a ninth consecutive win at Roazhon Park.
That represents their longest-ever run, while PSG have now lost twice in four matches, having gone unbeaten across their first 23 in all competitions this season.
Flashscore Man of the Match: Hamari Traore (Stade Rennais)