Carlo Ancelotti’s side currently trail Lyon by two points with Remi Garde’s men playing their game in hand against Nancy on Wednesday.
Regardless of the result against Nancy, Jallet feels a win for PSG in Sunday’s top-of-the-table clash would send out a message to their rivals.
“I don’t know if it will be decisive this time of the season, but if we win this game, I’m sure we would make an impression,” he told RMC.
“A win would also help us to cut down their lead [if Lyon win on Wednesday] so it’s a very important game. We should not take it lightly.
“We will concentrate on what we do best right now with a compact block which deploys beautiful play and which allows us to score goals.”
Zlatan Ibrahimovic helped himself to a hat-trick as PSG brushed aside Valenciennes 4-0 on Tuesday.