Paris Saint Germain's inexorable march toward Ligue 1 supremacy was dealt with a further blow Sunday as they succumbed to a narrow 1-0 defeat on home soil at the hands of Olympique Lyonnais.
The capital side, who only have the league to salvage a disappointing season after being knocked out of the French Cup and the Champions League, fell victim to Bradley Barcola's second-half goal and were left on 66 points from 29 games.
They lead second-placed RC Lens, who beat Stade Rennais 1-0 away on Saturday, by six points, with third-placed Olympique de Marseille also on 60 points after a 1-1 draw with Montpellier on Friday.
Earlier on Sunday, fourth-placed Monaco moved within three points of Marseille after a spectacular 4-3 home victory against Racing Strasbourg.
Lyon is ninth on 44 points.
"It's a lot. There is disappointment and anger because we concede to any opportunities. We lacked character and pride," said PSG coach Christophe Galtier.
"We don't follow the plan; we're not giving everything. However, the title is far from being in the pocket," said PSG defender Danilo Pereira.
The clash between PSG and Lyon started 10 minutes late after Laurent Blanc's side faced transportation issues.
"We could not go under a bridge, so we drove all around Paris," OL assistant coach Ludovic Giuly said.
The delay did not disturb Lyon.
They were awarded a penalty when Gianluigi Donnarumma made contact with Alexandre Lacazette in the area after a sharp counterattack from the visitors.
Lacazette hit the Italian keeper's right-hand post for the French striker's first miss from the spot this season.
PSG, who had their best chance in the opening half through Renato Sanches, were denied a penalty themselves on the stroke of the interval despite Dejan Lovren's handball and fell behind at 56 minutes.
Barcola connected with Sael Kumbedi's cross to finish it with a soft crossed shot to give Lyon the advantage.
PSG failed to react as they could not manage a shot on target before Hugo Ekitike's attempt was quickly blocked by Anthony Lopes, while Kylian Mbappe failed to make much of an impact.
France forward had his best chance in the first minute of stoppage time with a deflected shot that Lopes tipped away.
OL held firm until the final whistle and will head into Wednesday's French Cup semifinal full of confidence. At the same time, PSG, who were handed their fifth league defeat of the season, will need to regain their composure with a top-of-the-table clash against Lens in two weeks.