Valtteri Bottas was quickest in first practice for the British Grand Prix, with Lewis Hamilton second and Sebastian Vettel down in sixth.
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Practice one: Top three
1 Valtteri Bottas (Fin) Mercedes GP 1min 29.106secs
2 Lewis Hamilton (Gbr) Mercedes GP 1:29.184
3 Max Verstappen (Ned) Red Bull 1:29.604
Scroll down for all the times in full
Practice one report
Lewis Hamilton was beaten by his Mercedes team-mate Valtteri Bottas to top spot in opening practice for the British Grand Prix.
Hamilton, whose preparations for his home race at Silverstone have been overshadowed by his refusal to take part in a promotional event in London earlier this week, finished second in the order.
Bottas posted the best lap of the 90-minute session to finish 0.078 seconds clear of Hamilton with Red Bull's Max Verstappen in third, half a second off the pace.
Bottas, the Finnish driver who replaced defending champion Nico Rosberg at Mercedes, has emerged as a real contender in this year's title battle after he moved to within 15 points of Hamilton by virtue of his second victory of the campaign in Austria last Sunday.
For the championship leader Sebastian Vettel - who heads Hamilton by 20 points - he was a distant sixth at an overcast Silverstone this morning, 1.4 secs adrift of Bottas' best effort.
Vettel, 30, also became the first driver to trial the so-called 'shield', the FIA's third different concept aimed at improving cockpit protection.
The concept, made of transparent polycarbonate, is designed to sit in front of the driver and deflect any flying debris.
Vettel completed three laps with the device, which is now the governing body's preferred option over the 'canopy' and the 'halo'. The latter was described by Hamilton as the "worst-looking modification" in the sport's history.
The shield is expected to be used again after the summer break with the FIA aiming to carry out a full track test at September's Italian Grand Prix.
Back on track here, and Mercedes will be pleased by their early pace as Hamilton, and indeed Bottas, bid to reel in Vettel at the summit of the championship.
Aside from Hamilton's curious two-day break to Greece, the other talking point this week has been the decision by the British Racing Drivers' Club to trigger a release clause in its contract after 2019.
Such a move means this year's event could be one of the final grands prix to be staged at the Northamptonshire circuit unless a new deal with Formula One's owners Liberty Media is agreed.
As expected, the British fans were out in force with 350,000 spectators expected over the course of the weekend and a near sell-out crowd for Sunday's race.
Daniel Ricciardo finished fourth in the order ahead of Kimi Raikkonen. Fernando Alonso, who is set to serve a grid drop here following a series of penalties for changes to his Honda engine, was eighth.
Britain's Jolyon Palmer completed the fewest laps of any of the drivers after an earlier technical issue. The Renault driver finished 18th of the 20 runners, 3.3 secs slower than the leaders.
British Grand Prix: Practice one times in full
1 Valtteri Bottas (Fin) Mercedes GP 1min 29.106secs
2 Lewis Hamilton (Gbr) Mercedes GP 1:29.184
3 Max Verstappen (Ned) Red Bull 1:29.604
4 Daniel Ricciardo (Aus) Red Bull 1:29.942
5 Kimi Raikkonen (Fin) Ferrari 1:30.137
6 Sebastian Vettel (Ger) Ferrari 1:30.517
7 Daniil Kvyat (Rus) Scuderia Toro Rosso 1:30.895
8 Fernando Alonso (Spa) McLaren 1:30.993
9 Felipe Massa (Bra) Williams 1:30.999
10 Stoffel Vandoorne (Bel) McLaren 1:31.041
11 Carlos Sainz (Spa) Scuderia Toro Rosso 1:31.200
12 Esteban Ocon (Fra) Force India 1:31.210
13 Sergio Perez (Mex) Force India 1:31.297
14 Romain Grosjean (Fra) Haas F1 1:31.610
15 Lance Stroll (Can) Williams 1:31.684
16 Antonio Giovinazzi (Ita) Haas F1 1:32.031
17 Nico Hulkenberg (Ger) Renault 1:32.171
18 Jolyon Palmer (Gbr) Renault 1:32.450
19 Pascal Wehrlein (Ger) Sauber-Ferrari 1:33.029
20 Marcus Ericsson (Swe) Sauber-Ferrari 1:33.399