Gelson Martins continued his impressive form at Monaco after netting the opening goal after 18 minutes.
The second goal arrived eight minutes before the interval, with Rony Lopes firing past Lyon shot-stopper Anthony Lopez.
The win moves Monaco up to 16th spot, Lyon are unchanged in third spot.
Reims extended their unbeaten run in the league five matches with a 4-2 win over Montpellier at the Stade de la Mosson.
Remi Oudin bagged a brace while Arber Zeneli and Pablo Chavarría got the other goals for Reims.
Daniel Congre and Gaetan Laborde were on target for Montpellier, who have dropped to seventh.
Nicolas Pallois' 51st minute strike was enough to hand Nantes a 1-0 win over Bordeaux on Sunday afternoon.
CAEN missed the chance to move clear of the drop zone after drawing 1-1 with Toulouse.
Enzo Crivelli put the visitors ahead with his fifth league goal the season on the stroke of half, but Toulouse snatched a point thanks to Max Gradel equaliser in second-half stoppage time.
Olympique Marseille's top four hope took a dent following a 1-1 draw away to Rennes.
The visitors needed a 57th minute strike from Valere Germain to cancel out Benjamin Andre's seventh minute goal.