Formula One world champion Lewis Hamilton laid down a marker with the fastest lap in Friday's first practice for his home British Grand Prix, with Mercedes one-two at the top of the timesheets.
F1: Lewis Hamilton fastest in first practice at Silverstone
That was more than half a second faster than Ferrari's Sebastian Vettel, who leads fellow four-times champion Hamilton by a point in the standings after nine of 21 races with three wins apiece.
Hamilton's Finnish team mate Valtteri Bottas, with a new engine in his car after last weekend's retirement in Austria, was second fastest but 0.367 off the pace.
Australian Daniel Ricciardo was fourth for Red Bull with Ferrari's Kimi Raikkonen fifth and Max Verstappen, winner in Austria for Red Bull, sixth.
The 20-year-old Dutchman ended the session early after he was told to stop the car.
Haas's Romain Grosjean had a heavy crash at the first corner after failing to close the drag reduction system (DRS).
"The car is destroyed," the Frenchman, who was unhurt in the impact, said over the radio. "I'm very, very sorry guys. I think it was the bump. I missed the (DRS) button."
Grosjean's team mate Kevin Magnussen and McLaren's Fernando Alonso were called to see stewards for a "potentially dangerous manoeuvre" after an incident between them early on.
"Magnussen tried to hit me two times - in one and three," Alonso reported over the radio. "Very dangerous."