Valtteri Bottas set the pace in opening practice for the British Grand Prix as Sebastian Vettel became the first Formula 1 driver to trial the Shield cockpit protection device.
Bottas used the soft compound Pirelli tyres to clock a 1m29.106s at an overcast Silverstone, 0.379s quicker than Mercedes teammate Lewis Hamilton.
Championship leader Vettel, who was sixth fastest, headed out of the garage at the start of the session with the screen, which extends along the nose in front of the drivers, attached to his Ferrari.
The German completed a single installation lap and then returned to the garage, where Ferrari removed the device and switched attention to its weekend programme.
The medium compound – the hardest tyre available this weekend – was the rubber of choice for the early installation laps before Kimi Raikkonen fitted the supersofts and set the first time of the session with a 1m32.533s.
He traded quickest laps with the Red Bulls of Daniel Ricciardo and Max Verstappen, with the latter coming out on top initially.
Mercedes then sent Bottas out and the Finn went quickest on the soft tyres with a 1m30.788s.
Hamilton went three tenths faster with his first real effort on the softs but his teammate responded immediately to become the first driver to dip into the 1m29s.
The Finn continued to improve, gradually bringing his time down to a 1m29.106s, which is quicker than last year’s pole position time of 1m29.287s.
Red Bull emerged as the Mercedes team’s closest challenger, with Verstappen and Ricciardo third and fourth quickest respectively. However, both their laps were set on the supersofts.
Raikkonen was the leading Ferrari in fifth, 1.031s off the pace but four tenths quicker than teammate Vettel, who spun at Becketts and flat-spotted his tyres.
Fernando Alonso, who is running the more-powerful ‘Spec 3’ Honda engine this weekend, was eighth quickest on the supersofts, a tenth behind Toro Rosso’s Daniil Kvyat.
Felipe Massa, whose Williams team adopted a split approach with its upgrades by running different configurations on his and Lance Stroll’s cars, was ninth.
Stoffel Vandoorne made it two McLarens in the top 10, the Belgian just half-a-tenth slower than teammate Alonso.
Antonio Giovinazzi borrowed Kevin Magnussen’s Haas and set the 17th quickest time, nearly half-a-second off teammate Romain Grosjean.
Jolyon Palmer missed much of the opening part of the session, with his car up on stands in the garage, but the team eventually got him back out and the Briton ended up 18th quickest after 16 laps.