The attacker's goal lit up Stade de la Route de Lorient before Zlatan added a late second, as les Parisiens continue to close in on the title
With nearly an hour gone the match looked flat, yet Menez, who had endured a frustrating game to that point, took it upon himself to carve past four challenges before sliding a composed finish past Benoit Costil to secure the points for Carlo Ancelotti’s much-changed side.
In stoppage time, Zlatan Ibrahimovic made it 2-0 with a finish from little more than a yard out after substitute David Beckham clipped a ball across the box.
It was clear both from the team selection, which saw the likes of Thiago Silva, Lucas and Ezequiel Lavezzi benched, and the performance of PSG early on that minds had already turned partially towards the much-hyped midweek encounter, as Rennes enjoyed the better of the first half.
Sadio Diallo drew a good save from Salvatore Sirigu after a poor defensive header from Gregory van der Wiel, while Fantamady Diarra also drew a smart block from the Italian. Just before the break Jonathan Pitroipa smashed an effort just wide.
Ibrahimovic was present in PSG’s starting XI and was the team's major threat. Nevertheless, the lackluster nature of the Swede summed up his side’s performance and this was typified when he finished meekly after he expertly turned Jean-Armel Kana-Biyik.
At halftime Ancelotti introduced Beckham in place of the disappointing Marco Verratti, while the general tempo of the visitors’ play was lifted.
Menez, in particular, looked a good deal more dynamic and even before his wonderful goal he had threatened with a shot just over.
In the minutes after PSG had finally made the breakthrough it looked likely to fashion a second. Costil did well to deny Gameiro after Ibrahimovic’s miskick dropped kindly to him in the box, while the forward was also close to converting a Maxwell delivery from the left.
It was, however, Rennes which did much of the late running. PSG’s defending late on varied from the haphazard to the excellent, with Camara saving Sirigu’s blushes after he fumbled a cross and Van der Wiel making a key intervention when Anders Kondradsen burst into the box.
The hosts looked rather toothless throughout this encounter, and once PSG had grabbed the lead it appeared largely comfortable, although a Julien Feret shot from range did have Sirigu scrambling before Ibra finally put the game away.
Victory means that Ancelotti’s outfit has taken another big step towards a first title in nearly two decades, while it also provides an excellent platform for its trip to Barcelona, which has been the team's main focus for the last week.