Red Bull's Max Verstappen clocked in fastest in the opening practice session at Silverstone for this weekend's British Grand Prix, the Dutchman edging Mercedes' Lewis Hamilton by a little under half a second.
Verstappen achieved his best lap during a run on the soft tyre while Hamilton never appeared to force the issue during the morning, which Ferrari's Sebastian Vettel was forced to sit out after an intercooler problem was uncovered on his car.
Racing Point's Lance Stroll was third, while Alex Albon and Charles Leclerc rounded off the top five.
It was a close call, but Racing Point super-sub Nico Hulkenberg was up and running at Silverstone just in time for the start of free practice.
The session kicked off under scorching temperatures and clear blue skies, and the Hulk was logically among the first drivers to hit the track and kick off the rust collected since his last Grand Prix at Abu Dhabi last year.
The first mishap of the day came courtesy of Kimi Raikkonen who ventured into the gravel at Turn 7 after the Finn applied a bit too much power on the exit of Luffield.
Not to be outdone by the Iceman, his Alfa Romeo teammate Antonio Giovinazzi felt the need to spin at Becketts, the Italian clumsily shedding debris and rubber on his way back to the pits and bringing out the red flag.
Meanwhile, Max Verstappen had positioned himself at the top of the screens, followed by Lando Norris and Renault boys Esteban Ocon and Daniel Ricciardo.
But there was drama in the Ferrari garage where a significant intercooler issue on Sebastian Vettel's SF1000 spelled the end to the German's session, with the team forced to strip the car and conduct repairs in time for FP2.
When the session got back underway, Bottas sprung to the top with a lap in 1m28.869s that comfortably displaced Verstappen, while Racing Point's Lance Stroll slotted into P2, just edging Max and Hamilton.
But halfway through FP1 the reigning world champion took command, popping in a 1m28.343 on soft tyres to lead Bottas by 0.176s, Verstappen and Stroll. However, Hamilton was heard complaining of tyre graining, calling the soft rubber "terrible".
There was no sign of Charles Leclerc in the top ten, the Monegasque lingering down the order as he did the set-up work for both Ferraris.
However, a diligent Hulkenberg was sat P9 at the same point of the session, about six tenths off from Stroll. Not too shabby for a last minute F1 returnee although the German admitted he wasn't sitting too comfortably in the RP20.
"My right ass-cheek is getting a bit numb, there's a big pressure point down there," he quipped over the radio.
With 30 minutes to go, Verstappen upped the ante, putting a 1m27.422 on the board that demoted Hamilton to second by 0.474s.
Meanwhile, Leclerc - shod on the medium tyre - finally got going, moving up to fifth just behind Stroll and Alex Albon.
Improvements were few and far between in the closing stages of the session, and the order at the top remained unchanged, with Verstappen topping the times.
Behind P5 man Leclerc, Bottas, Ocon, Ricciardo followed while Hulkenberg - all things considered - was a remarkable ninth, with AlphaTauri's Daniil Kvyat rounding off the top ten.
Both McLarens ended the morning in the second half of the field, Sainz and Norris respectively P12 and P13.
Verstappen was the man in charge in FP1, perhaps signaling that Red Bull's aero tweaks are having a positive effect on the team's RB16, while Mercedes has yet to stretch its legs.
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