Marseille, gunning for their first trophy since they last became French champions in 1992, lead Girondins Bordeaux on goal difference, yet Gerets seems impervious to pressure with three matches left.
"We are going to enjoy a good beer," Gerets, who will leave the club at the end of the season, told OM's website after his team beat Nice on Wednesday for their seventh consecutive away win.
"(At Nice), the players were happy, happy to be footballers."
Midfielder Mathieu Valbuena, however, was a little more focused on Sunday's match than his manager.
"It's auspicious for what is coming next," the diminutive Valbuena said. "We will be up against something extremely tough. We will have to raise our level of play.
"If we keep our state of mind, we are going to experience something amazing."
Lyon, who are seven points adrift of the leading duo, will welcome back winger Sidney Govou, who has nursed an Achilles' injury, for the Marseille trip.
Bordeaux, who won 2-1 at Valenciennes on Wednesday to stay level on points with Marseille, will also be trying to secure direct access to next season's Champions League against Le Mans.
"We are closing in on the Champions League. It is important to keep the gap (on) the third-placed team," coach Laurent Blanc told his club's website.
