The 27-year-old and his team-mates will tackle Carlo Ancelotti's side on October 7, but Valbuena is unconcerned at present, with other fixtures to come before that clash.
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"Everyone talks about PSG today," he said in an interview with RMC Sport.
"We know these are very exciting matches, but there is another match before. We must think about Valenciennes to continue our league run and then face PSG in the best form.
"Paris are not unbeatable. We have the ability to do something great. It will be very hard, but they are not unbeatable."
Marseille are currently top of Ligue 1 after winning all of their opening six games.