Ezequiel Lavezzi struck just before the half-hour mark as the hosts took the lead and held on to record a narrow victory and extend their winning streak to five matches in all competitions.
Laurent Blanc's reigning champions sit one point behind Lyon and two ahead of third-placed Marseille, both of whom have yet to play this weekend, while the defeat leaves Rennes 10th.
Former Newcastle midfielder Yohan Cabaye played the full 90 minutes.