The Lyon midfielder remained modest in his side's ambitions, despite being five points ahead of Carlo Ancelotti's side, who he believes are still the side to beat
Carlo Ancelotti's men suffered a shock 2-1 reverse at Nice on Saturday, compounding the misery after a week in which they were knocked out of the Coupe de la Ligue on penalties to Saint-Etienne.
In contrast, Lyon surged to the summit after thrashing title rivals Olympique de Marseille 4-1, before narrowly securing a 1-0 victory over champions Montpellier on Saturday to increase their lead over PSG to five points.
Nevertheless, Grenier believes that the sheer quality in les Parisiens' squad should see them rebound from their poor form.
"They are five points behind, but Paris should pass through their bad form. They remain favourites given their team," the 21-year-old told RMC Sport.
"Our form is a result of hard work. For now, we are very happy to be first. For now, we have done well."
Remi Garde's side sit top of Ligue 1 with 31 points and encounter PSG in two weeks' time.