Paris: Nice slumped to their first defeat of the season on Saturday as they lost 1-0 at Nantes and missed the chance to reclaim top spot in Ligue 1.
Florent Mollet's first-half strike was enough to get new coach Jocelyn Gourvennec off to a winning start at the Stade de la Beaujoire, where he took over from Pierre Aristouy this week.
Nice had gone eight games without conceding since their 3-2 victory over Paris Saint-Germain in mid-September, but the visitors saw their unbeaten start ended after they fell behind in a match for the first time this season.
"It's a logical defeat," said Nice coach Francesco Farioli.
"We need to move on from it. This loss definitely hurts. But, like with our wins, we need to forget about this defeat.
"We had chances to take the lead or equalise. We came up against a goalkeeper on top form," he added.
Nice's defeat will allow leaders PSG to pull four points clear if they win at Le Havre on Sunday.
Lens shook off their midweek Champions League humiliation by Arsenal to condemn crisis-hit Lyon to a 3-2 defeat in the club's first match since the exit of coach Fabio Grosso.
Irish defender Jake O'Brien volleyed Lyon in front from a corner at Stade Bollaert in northern France, but last season's Ligue 1 runners-up levelled midway through the first half courtesy of Wesley Said.
Przemyslaw Frankowski put Lens ahead with a penalty early in the second half before O'Brien poked home a flick-on at another corner to equalise.
Frankowski grabbed the winner on 74 minutes as Lens closed out a fourth win in five league games and extended their unbeaten run in the top flight to nine despite losing Florian Sotoca to a late red card.
Lens made a dreadful start to the season and picked up one point from their first five fixtures.
Franck Haise's side have righted the ship domestically but were dumped out of the Champions League on Wednesday following a crushing 6-0 loss away to Arsenal.
Lyon slid to an eighth defeat in 13 matches and remain rooted to the bottom of the table, five points from safety and on the hunt for a new coach after Grosso was stood down from his position on Thursday.
The 46-year-old Italian, a World Cup winner in 2006, lasted just over two months in the hot seat after he replaced Laurent Blanc on September 16.
It was an unhappy time in the dugout for Grosso, who oversaw just one win in seven matches and was left requiring stitches to his face in October after the Lyon team bus was attacked on its way to a game at Marseille.