Romain Grosjean has revealed he is not enjoying equal equipment with his Haas teammate Kevin Magnussen.
Neither of the pair are competitive at Paul Ricard, as they lament the Pirelli tyre problems that have plagued the American team's 2019 season.
"We do not have a car that works well," Frenchman Grosjean said at his home race.
"For me, this has been the case for two weekends. I do not have the evolution of the rear suspension that Kevin has already. Here, it is really costing me."
But Haas' well-documented struggle on the Pirelli tyres is also a big problem at Paul Ricard, with boss Gunther Steiner saying this weekend it is "strange".
"If you look at the sessions, a team is suddenly fifth best and then falls back down again," he told Ekstra Bladet newspaper.
"Everyone is all over the place and we don't understand it."
Speaking to French media, Grosjean agrees: "Sometimes it's the front that slides, sometimes the rear. You never know what to expect.
"We badly blamed the tyres at the beginning of the season, but the track has been very hot here and still we do not progress," he told Canal Plus broadcaster.
"We have slightly missed the development race and will have to react. There is wind, tyres, etc, but you cannot always hide behind excuses."
