Silverstone - Mercedes made a statement of intent in the first British Grand Prix practice on Friday with Valtteri Bottas leading home favourite Lewis Hamilton at the top of the timesheets as Ferrari was left far behind.
The Finn, keeping up the momentum after winning in Austria, was nearly half a second faster than his closest non-Mercedes rival with the 2017 Formula One cars looking significantly quicker and the champions in ominous form.
Red Bull's Dutch teenager Max Verstappen, who has had five retirements in the last seven races, and Australian Daniel Ricciardo were third and fourth respectively at an overcast Silverstone.
"Mercedes look really strong but we look to be in the fight with Ferrari. At the moment we're battling Ferrari and not Mercedes," commented Ricciardo, who has been on podium for five races in a row.
Hamilton, who will be chasing his fifth British Grand Prix victory and fourth in a row on Sunday, was 0.078 off his team-mate's best time of one minute 29.106 seconds.
Bottas's time was quicker than Hamilton's 2016 pole position of 1:29.287.
Ferrari's world championship leader Sebastian Vettel, who is 20 points clear of the Briton after nine of 20 races, was sixth quickest and behind team-mate Kimi Raikkonen - who was more than a second slower than Bottas.
"Even on TV the cars look awesome," said Red Bull principal Christian Horner. "I think the drivers are really enjoying that and it's just going to get quicker as the circuit rubbers in."
Vettel started the morning by trying out the new 'shield', the first driver to experience the transparent open canopy system designed to protect the head from flying debris and bouncing wheels.
Governing body FIA has been focusing on that concept rather than a 'halo' cockpit protection system that was extensively tested last season to a mixed response from teams and drivers.
"It's agreed to put it on the car for next year. It is a really accelerated programme as the decision was taken a couple of months ago," Williams technical head Paddy Lowe told Sky Sports television.
"We're very interested to hear the feedback from Sebastian, especially on visibility. I thought it looked pretty good.
"We're worried about reflections but there may be solutions to that. We will be testing it on various cars over the coming months."
1. Valtteri Bottas (Finland) Mercedes 1:29.106
2. Lewis Hamilton (Britain) Mercedes 1:29.184
3. Max Verstappen (Netherlands) Red Bull - TAG Heuer 1:29.604
4. Daniel Ricciardo (Australia) Red Bull - TAG Heuer 1:29.942
5. Kimi Raikkonen (Finland) Ferrari 1:30.137
6. Sebastian Vettel (Germany) Ferrari 1:30.517
7. Daniil Kvyat (Russia) Toro Rosso - Renault 1:30.895
8. Fernando Alonso (Spain) McLaren 1:30.993
9. Felipe Massa (Brazil) Williams-Mercedes 1:30.999
10. Stoffel Vandoorne (Belgium) McLaren 1:31.041
11. Carlos Sainz Jr (Spain) Toro Rosso - Renault 1:31.200
12. Esteban Ocon (France) Force India - Mercedes 1:31.210
13. Sergio Perez (Mexico) Force India - Mercedes 1:31.297
14. Romain Grosjean (France) Haas - Ferrari 1:31.610
15. Lance Stroll (Canada) Williams-Mercedes 1:31.684
16. Antonio Giovinazzi (Italy) Haas - Ferrari 1:32.031
17. Nico Huelkenberg (Germany) Renault 1:32.171
18. Jolyon Palmer (Britain) Renault 1:32.450
19. Pascal Wehrlein (Germany) Sauber - Ferrari 1:33.029
20. Marcus Ericsson (Sweden) Sauber - Ferrari 1:33.399