Red Bull were back on top during FP3 at the Miami International Autodrome, with Sergio Perez lapping quickest.
In the final practice session ahead of qualifying for the inaugural Miami GP, it was the Mexican driver who set the fastest lap with a 1:30.304.
Charles Leclerc finished second, 0.2 seconds behind, while Max Verstappen - at one stage lucky to avoid contact with the barrier - was 0.3 seconds slower.
But Mercedes' struggles appear to have returned, despite promising FP1 and FP2 sessions. Lewis Hamilton finished 15th, with George Russell 17th.
The full results from FP3 for the Miami GP can be seen below:
Result Free practice 3 - Miami
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