Ferrari set a daunting pace ahead in second practice for the French Grand Prix as Carlos Sainz headed a Scuderia one-two.
The Spaniard - who will take a 10-place grid penalty for Sunday's race after changing to a third control electronics component - finished a tenth faster than team-mate Charles Leclerc, setting a benchmark time of a one minute, 32.527secs.
Max Verstappen finished half a second adrift in third for Red Bull, who had been less than a tenth behind Leclerc in the first session. But the reigning champion was faster than both Ferraris on the medium tyre runs in the opening half an hour.
Mercedes' upgrades haven't worked quite how the team would have desired with George Russell fourth, seven-tenths behind Sainz whilst Lewis Hamilton returned to the cockpit with the fifth fastest time.
The seven-time champion had stepped aside for Nyck de Vries to complete the first of two obligated rookie runs in FP1, though was able to get straight back up to speed having completed a driver coaching role over the first hour.
But the gap from the Silver Arrows to the top was reduced from first practice, providing hope of a challenge across the weekend.
Lando Norris put McLaren's updates to good use to finish six with Daniel Ricciardo in ninth as Pierre Gasly and Kevin Magnussen split the two MCL36s.
Sergio Perez rounded out the top 10 for Red Bull having set his soft-tyre lap later in the session than the majority of the field.
Mick Schumacher caused the most drama of a relatively straightforward session with a spit into the double-apexed Le Beausset whilst on his early medium tyre run, whilst Russell ran wide over the exit curb at the same corner.
But Sunday's grand prix could see a change in the order with Mercedes team radio suggesting high degradation for Ferrari on Leclerc's high-fuel run in the closing stages.
French Grand Prix second practice results
1. Carlos Sainz [Ferrari] 1:32.527secs
2. Charles Leclerc [Ferrari] +0.101s
3. Max Verstappen [Red Bull] +0.550s
4. George Russell [Mercedes] +0.764s
5. Lewis Hamilton [Mercedes] +0.990s
6. Lando Norris [McLaren] +1.080s
7. Pierre Gasly [AlphaTauri] 1.379s
8. Kevin Magnussen [Haas] +1.401s
9. Daniel Ricciardo [McLaren] +1.457s
10. Sergio Perez [Red Bull] +1.533s
11. Fernando Alonso [Alpine] +1.732s
12. Valtteri Bottas [Alfa Romeo] +1.737s
13. Sebastian Vettel [Aston Martin] +1.893s
14. Yuki Tsunoda [AlphaTauri] +2.013s
15. Lance Stroll [Aston Martin] +2.068s
16. Alex Albon [Williams] +2.126s
17. Zhou Guanyu [Alfa Romeo] +2.127s
18. Esteban Ocon [Alpine] +2.133s
19. Mick Schumacher [Haas] +2.668s
20. Nicholas Latifi [Williams] +2.885s