Monaco edged visiting Brest 1-0 on Sunday to start the Ligue 1 New Year by tightening their grip on fourth and closing in on a Champions League spot.
Aleksandr Golovin smashed in the only goal from outside the penalty area as the home team did just enough to win. They moved level with Marseille, who are third and visit Montpellier on Monday.
Brest dominated the rest of the second half but could not score and remained 17th and in the relegation places.
Nantes jumped from 16th to 14th as they beat struggling Auxerre with a 73rd-minute goal from Marcus Coco.