- Bradley Barcola (56')
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 of Bradley Barcola's second half goal and were left on 66 points from 29 games.
Earlier on Sunday, fourth-placed Monaco moved within three points of Marseille after a spectacular 4-3 home victory against Strasbourg.
Lyon are ninth on 44 points.
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," Lyon assistant coach Ludovic Giuly said.
The delay did not disturb Lyon.
Lacazette, however, 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 they fell behind on 56 minutes.
Barcola connected with Sael Kumbedi's cross to finish it off with a soft crossed shot to give Lyon the advantage.
The France forward had his best chance in the first minute of stoppage time with a deflected shot that was tipped away by Lopes.
Lyon held firm until the final whistle and will head into Wednesday's French Cup semifinal full of confidence while 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.
- Francois Letexier
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