There will now be a triple-header, with the French event moved forward by a week to June 20 followed by back-to-back races in Austria at the Red Bull Ring.
Grosjean's outing with Mercedes was recently confirmed, representing a return to F1 machinery for the Frenchman for the first time since his fiery accident at the Bahrain GP last year.
It was intended to consist of a test on June 29 as well as demo laps at the Paul Ricard circuit on race day, however, the French race now clashes with the IndyCar Series event at Road America.
Providing an update on social media, Mercedes confirmed: "[The] full test on the 29th June will be going ahead, as planned, but the demo laps on the Sunday of the French GP now clash with an IndyCar race so that won’t be possible"
The revised French GP date now clashes with Romain's IndyCar race so that means his demo laps on the Sunday won't be possible. But the full test day in W10 remains unchanged from the original plan and will still go ahead!
— Mercedes-AMG PETRONAS F1 Team (@MercedesAMGF1) May 14, 2021