Lyon let slip the perfect chance to pile the pressure on French league leaders Paris Saint-Germain when they were held to a 1-1 draw at Brest on Sunday, while Marseille reclaimed third place after beating Troyes 2-1.
With the expensively-assembled Paris outfit losing 1-0 at lowly Reims, Lyon had the chance to draw level on points, but a lacklustre display on a rough-and-ready looking pitch in Brest left them two points adrift in the title race.
"The challenging surface is not an excuse. It took us time to get into the match, we know that teams fighting to stay in the league rely heavily on their home matches," said Lyon striker Bafetimbi Gomis.
Teammate Milan Bisevac also emphasised the importance of Remi Garde's men remaining resilient in their quest for the league crown.
"We have to be strong, the title is going to undoubtedly be decided against the smaller teams. We can't give up, even if Paris are favourites," said the Serbian.
"It's a difficult league: we didn't win today, Paris lost yesterday. It's difficult for us and Paris. The strongest mentally will win."
It took Brest only eight minutes to get their heads in front as Moroccan midfielder Kamel Chafni went on a run down the left, exchanged passes with Magaeye Gueye on the edge of the area and strode forward, beating Steed Malbranque to the ball and planting his low shot firmly in the bottom right hand corner beyond Remy Vercoutre's outstretched hand.
Seven minutes into the second half, Lyon were back on terms as Lisandro Lopez burst through and Brest defender Tripy Makonda could only watch as the Argentine's shot ricocheted into the empty net off his chest.
Lyon had a chance to steal all three points with 10 minutes to go as Arnold Mvuemba teed up Lisandro but his shot was cleared off the line by Florian Lejeune with goalkeeper Alexis Thebaux beaten.
Worse was to follow in stoppage time when Gomis volleyed wide with the goal at his mercy for what proved to be the final kick of the match.
Meanwhile, Marseille wrested control of the final Champions League spot back from Saint-Etienne, climbing to within three points of Lyon, and five behind PSG, after grinding out a 2-1 home win over basement club Troyes.
Brazilian striker Marcos capitalised on a defensive lapse from Nicolas N'Koulou to put the visitors ahead on 70 minutes at Stade Velodrome, but two goals in as many minutes provided the perfect tonic for Marseille after successive defeats to bitter rivals PSG.
Substitute Modou Sougou sparked the recovery, crossing for N'Koulou whose bundled effort was turned into his own net by the unwitting Florian Jarjat nine minutes from the end.
The Senegalese winger was then again instrumental in the winning goal as he teed up Andre-Pierre Gignac to slot home from six yards out after a clever exchange of passes with Mathieu Valbuena.
"It's a relief," Valbuena told beIN Sport afterwards.
"We started very well again. We had chances to score. Unfortunately, we conceded the goal and that made us react, not for the first time this season, and we scored two goals in a row.
"We apparently have to take a blow each time before reacting, it's a shame," he added.