Defending champion Lewis Hamilton laid down a marker by dominating practice on Formula One's return to France.
Hamilton was fastest in both sessions at the Paul Ricard circuit as he bids to usurp rival Sebastian Vettel at the top of the standings.
Ferrari's Vettel is one point clear of Hamilton, but the British driver and his Mercedes team held the edge in Le Castellet on Friday.
The 33-year-old Englishman lit up the time sheets in the day's opening running before returning to its summit later in the day.
Hamilton, armed with a new Mercedes engine, posted a best lap of one minute and 32.539 seconds to finish clear of the rest.
Daniel Ricciardo was second for Red Bull, three quarters of a second behind the Mercedes, with his team-mate Max Verstappen third.
Ferrari traditionally underplay their hand on Friday, and Kimi Raikkonen and Vettel finished fourth and fifth respectively.
Vettel, who claimed his third win of the season in Canada a fortnight ago, was more than one second down on Hamilton.
Valtteri Bottas finished seventh in the sister Mercedes after sitting out much of the second session with a water leak on his car.
Earlier in the day, Marcus Ericsson's dramatic crash brought a premature end to the opening running.
Swedish driver Ericsson lost control at the left-handed 100mph Turn 12, sliding down the long run-off area before hitting the tyre barrier.
His Sauber then started billowing flames from the rear. Ericsson, who could not see the inferno behind him, remained in the car.
Ericsson had to be alerted to the danger over the radio as marshals ran over with fire extinguishers and he hastily leapt out of the car.
The session was immediately red-flagged and Ericsson, 27, emerged unscathed from his charred Sauber.
It marked the first time an F1 car has been on fire since this season's introduction of the halo, the controversial cockpit safety device which sits above the driver.
There was drama in the second session, too, as Sergio Perez lost his left-rear wheel. The tyre worked its way off the Mexican's Force India and bounced along the track.
The red flags were deployed with Perez stranded in his three-wheeled car at Turn 7.
McLaren are enduring yet another agonising season, and they have shown no improvement in France.
Fernando Alonso, who completed the second leg in his pursuit of motor racing's Triple Crown with victory at Le Mans last weekend, was eighth, 1.9 seconds off the pace.
The Spaniard, 36, also spun in the closing moments before limping back to the pits. Alonso's team-mate Stoffel Vandoorne finished in 13th.