Leclerc fastest in upgraded Ferrari as Mercedes hit trouble before Sprint Qualifying

Charles Leclerc was fastest in Miami Grand Prix Practice in a heavily-upgraded Ferrari as both Mercedes drivers suffered problems on Formula 1's return.

Leclerc set two lap times quick enough to top the only practice session to beat Red Bull's Max Verstappen by 0.297s, with the early indications suggesting Mercedes no longer have the outright fastest car going into Sprint Qualifying at 9.30pm later on Friday, live on Sky Sports F1.