The former Porto striker's prospects of leading his side into their encounter on Saturday have diminished after he picked up a knock in a recent friendly
The 29-year-old appeared to aggravate an old injury to his right thigh he first picked in late 2010 when he limped off the field in the 33rd minute of Lyon's friendly victory over Montreal Impact.
Following his latest setback, Lopez is all but certain to have to watch his team-mates from the stands, and the start of the Stade de Gerland side's Ligue 1 campaign on August 11 appears to be out of reach.
"I don't know [about Saturday's clash], we'll see. I fear it's a spasm," the Argentine explained to L'Equipe.
Lyon defeated Quevilly in the final of last season's Coupe de France to set up their date with Montpellier, but slumped to a disappointing fourth-placed finish in Ligue 1.