Six points behind leaders Paris Saint-Germain, Lens passed Marseille for the second automatic Champions League qualification spot on goal differential.
With a loss in their first game after winning 2-0 at PSG prior to the international break, Rennes’ erratic season continued and they remained in fifth place.
Openda, a Belgian striker, nodded Florian Sotoca’s cross across the goal line from close range to score his sixth goal in three league games and 15th goal overall in Ligue 1. Warmed Omari, a Rennes center back, had a late attempt disallowed for offside, giving Lens a scare.
Marseille missed the opportunity to close the gap on defending champions PSG, who play Lyon at home on Sunday, by four points after Montpellier held them to a 1-1 draw at home on Friday.
