George Russell emerged quickest from practice for the second time this year after a worrying session for Carlos Sainz and reigning F1 champion Max Verstappen ahead of this weekend's inaugural Miami Grand Prix.
A number of updates that includes new front and rear wings have propelled Mercedes back to the front at the Miami International Autodrome where the level of porpoising that has plagued the W13 this season has been significantly reduced.
After finishing second quickest to championship leader Charles Leclerc in FP1, Russell traded places with the Monégasque for the second session as he posted the only time under 90 seconds so far with a lap of 1:29.938s.
Russell was also quickest in FP2 in Imola, although that session was not as important given it sat between qualifying and the sprint race, with this far more representative in terms of Mercedes' improving pace and stability.
Leclerc was just a tenth of a second adrift, followed closely by Red Bull's Sergio Perez and seven-time F1 champion Lewis Hamilton in his Mercedes.
As for Sainz, after crashes in the last two races in Australia and at Imola, his sorry season continued with another incident 17 minutes into FP2 and at a time when he was leading the way on the medium-compound tyre with a lap of 1:30.964s.
Making his way through the twisty part of the middle sector, Sainz was carrying too much speed emerging out of turn 13 which resulted in him losing the back end of his car and careering side-on into a barrier at the entry of 14.
Following a 12-minute red-flag period, on his first lap on track following a gearbox change, Verstappen initially complained about the steering on his RB18 locking. As he then slowly made his way back to the team garage, his brakes caught fire.
It was later confirmed Verstappen's car had sustained a hydraulics issue, leaving him 19th in the standings without a time to his name, with only Alfa Romeo's Valtteri Bottas below him after the Finn's crash in the first session.
Behind Hamilton, Alpine's Fernando Alonso was 0.434s adrift of Russell, with the two-time champion followed by McLaren's Lando Norris and AlphaTauri's Pierre Gasly.
Alfa Romeo's Zhou Guanyu, the second Alpine of Esteban Ocon and Haas driver Kevin Magnussen completed the top 10, the latter suffering a minor spin late on.
There was a second red flag prior to Magnussen's incident, with Williams' Nicholas Latifi pulling over to the side of the circuit after complaining of a technical problem.
Miami Grand Prix second practice results
1. George Russell [Mercedes] 1:29.938s
2. Charles Leclerc [Ferrari] +0.106
3. Sergio Perez [Red Bull] +0.212
4. Lewis Hamilton [Mercedes] +0.241
5. Fernando Alonso [Alpine] +0.434
6. Lando Norris [McLaren] +0.597
7. Pierre Gasly [AlphaTauri] +0.609
8. Zhou Guanyu [Alfa Romeo] +0.922
9. Esteban Ocon [Alpine] +0.923
10. Kevin Magnussen [Haas] +0.983
11. Carlos Sainz [Ferrari] +1.026
12. Daniel Ricciardo [McLaren] +1.270
13. Yuki Tsunoda [AlphaTauri] +1.322
14. Sebastian Vettel [Aston Martin] +1.455
15. Mick Schumacher [Haas] +1.649
16. Lance Stroll [Aston Martin] +1.693
17. Alex Albon [Williams] +1.772
18. Nicholas Latifi [Williams] +2.975
19. Max Verstappen [Red Bull] no time
20. Valtteri Bottas [Alfa Romeo] no time