Charles Leclerc edged fellow F1 title protagonist Max Verstappen in first practice for the French Grand Prix as Lewis Hamilton looked on from the Mercedes garage.
The Ferrari driver, winner of the last race in Austria to revitalise his championship ambitions, posted a lap of one minute 33.930secs around the Paul Ricard Circuit, finishing just 0.091s ahead of Red Bull's reigning champion.
As for Hamilton, under new regulations from this season designed to give younger drivers an FP1 opportunity, Hamilton opted to sit out this session at Le Castellet.
For the seven-time F1 champion, there was the unusual sight of him standing in his team's garage while another driver - on this occasion reserve Nyck de Vries - drove his car.
The reigning Formula E champion did not disgrace himself, finishing ninth quickest and half-a-second adrift of fourth-placed George Russell in the other W13.
Russell, though, finished a second behind Leclerc at a track where the expectation is Mercedes will perform well given the venue's smooth surface and with the team now appearing to be on top of the porpoising/bouncing woes that has afflicted its cars.
In temperatures hitting 30 degrees Celsius, sending the track temperature soaring to 60, it was Leclerc who ultimately had the final say in an hour-long session in which Ferrari team-mate Carlos Sainz and Verstappen had both topped the leaderboard.
Sainz, who will take a 10-place grid penalty for a change of the control electronics unit - and with potentially more penalties to come over the weekend - had to settle for the third-best time, 0.338s behind Leclerc.
Pierre Gasly was fifth in a heavily upgraded AlphaTauri, followed by Sergio Perez who took his Red Bull for a spin early on, with the Mexican just managing to keep his car out of the barriers.
Lando Norris, in a McLaren also sporting a comprehensively updated car, was 1.302s back in seventh place ahead of Williams' Alex Albon and then De Vries, with Daniel Ricciardo completing the top 10.
On home soil, Alpine duo Esteban Ocon and Fernando Alonso were only 13th and 15th, sandwiching Aston Martin's Sebastian Vettel.
In stark contrast to Albon's fine performance and 1:35.414s lap time, team-mate Nicholas Latifi propped up the standings and just over 1.5s back.
French Grand Prix first practice results
1. Charles Leclerc [Ferrari] 1:33.930s
2. Max Verstappen [Red Bull] +0.091s
3. Carlos Sainz [Ferrari] +0.338s
4. George Russell [Mercedes] +0.951s
5. Pierre Gasly [AlphaTauri] +1.049s
6. Sergio Perez [Red Bull] +1.244s
7. Lando Norris [McLaren] +1.302s
8. Alex Albon [Williams] +1.484s
9. Nyck de Vries [Mercedes] +1.496s
10. Daniel Ricciardo [McLaren] +1.730s
11. Zhou Guanyu [Alfa Romeo] +1.746s
12. Lance Stroll [Aston Martin] +1.880s
13. Esteban Ocon [Alpine] +1.898s
14. Sebastian Vettel [Aston Martin] +1.921s
15. Fernando Alonso [Alpine] +1.945s
16. Mick Schumacher [Haas] +2.092s
17. Kevin Magnussen [Haas] +2.174s
18. Yuki Tsunoda [AlphaTauri] +2.197s
19. Robert Kubica [Alfa Romeo] +2.402s
20. Nicholas Latifi [Williams] +3.113s