Red Bull's Pierre Gasly unexpectedly led the field in the first free practice session for the British Grand Prix at Silverstone, the Frenchman comfortably outpacing Mercedes' Valtteri Bottas.
Gasly's best lap, achieved on the soft tyre, came in the closing stages of a session dominated up to then by Mercedes. The Red bull charger edged Bottas by 0.456s while Max Verstappen was third, 0.836s adrift.
Lewis Hamilton clocked in fourth in front of the Ferrari pair of Charles Leclerc and Sebastian Vettel, while Renault's Nico Hulkenberg and Daniel Ricciardo were seventh and eight respectively.
Toro Rosso's Alex Albon and McLaren's Carlos Sainz rounded off the top ten.
Silverstone provided runners with a relatively cool environment to kick off the British Grand Prix weekend, with air temperatures at 19°C while the track itself was heated at 30°C under an overcast sky.
The event is a home race for most of the teams on the grid and McLaren was the first among the locals to send out its drivers, with Lando Norris and Carlos Sainz drawing loud encouragements from the crowd.
Installation laps were the norm in the first few minutes of running, but Haas' Romain Grosjean provided the entertainment, the Frenchman spinning as early as the pitlane exit and losing his front wing before shedding other bits of bodywork as he coasted back to base!
Grosjean's antics warranted a virtual safety car and when it was lifted, Mercedes sprung into action, with Bottas putting himself ahead with a 1m24.604s.
Shortly after, Williams' George Russell went across the grass at Brooklands while Norris spun at Club, but both drivers found their way back on the track without any drama.
Behind the two Mercedes, Ferrari lined up third and fourth with Vettel preceding Leclerc, while max Verstappen and Pierre Gasly followed suit.
Meantime, Kimi Raikkonen's Alfa Romeo was seen stranded on the outside of Luffield, the victim of an apparent mechanical problem as indicated by the whiff of smoke seen at the rear of the C38.
Pushing on soft tyres, the Silver Arrows distanced themselves from their rivals by a few additional tenths.
Clouds that had built up overhead started releasing a bit of light rain, increasing the amount of off-track excursions that Silverstone's new smooth surface had induced earlier in the session.
The circuit went quiet as everyone sought refuge in their respective garages.
With 20 minutes left on the clock, the sun shined through once again and the action resumed, with Verstappen improving his time on a second set of soft tyres to position himself third between Mercedes' and Ferrari's chargers.
But a final effort by the Dutchman pushed him to second, 0.380s behind Bottas. The good time appeared to underline once again Verstappen's edge over Gasly, but the Frenchman suddenly put a consistent lap together that brought him within 0.086s of Bottas.
The 'Gas-man' - perhaps running very low fuel levels - went one better however and overhauled the Finn by almost half a second to surprisingly conclude the session at the top of the time sheet!