British Grand Prix 2015: Nico Rosberg beats Lewis Hamilton in first practice but Mercedes referred to stewards after German breaks down

Rosberg's car was covered up as it was recovered to the pits following a hydraulic failure

(Getty Images)

Nico Rosberg overcame a hydraulic failure in the opening practice session for the British Grand Prix to lay down a title marker to home favourite Lewis Hamilton.

Rosberg spent much of the 90-minute session watching with headphones on from the back of the Mercedes garage after his car stopped on track with only five laps under his belt.

But the German made it back out on to the track with a little under 10 minutes remaining after Mercedes successfully changed his gearbox.

He posted a best lap of one minute 34.274 seconds to finish less than a tenth of a second faster than Hamilton at a warm and sunny Silverstone.

The Briton, who emerged unscathed from a high-speed spin on the exit of Stowe moments before Rosberg stopped, had spent much of the session leading the way before his fastest time of 1min 34.344secs was pipped by Rosberg.

Max Verstappen, the impressive 17-year-old, was third in his Toro Rosso with Ferrari's Kimi Raikkonen in fourth. Verstappen's team-mate Carlos Sainz was next up, and Sebastian Vettel, celebrating his 28th birthday on Friday, was sixth fastest.

It was business as usual for Hamilton, and so too for Jenson Button as he completed only 10 laps in what could be his final Silverstone outing.

The Briton spent much of the morning session kicking his heels in the McLaren garage before he emerged on track with just 12 minutes left. He finished 18th, 4.586 seconds slower than Hamilton.

Fernando Alonso's fortunes weren't much better. The double world champion failed to post a lap in the first hour before ending the session one place higher than his team-mate in 17th, almost four seconds adrift of Rosberg.

Susie Wolff, the Williams reserve driver, was 13th, the best part of three seconds off the leading pace. Fellow Briton Jolyon Palmer was 14th in his Lotus as he deputised for Romain Grosjean while Manor driver Will Stevens was 19th, only one tenth slower than Button.

Mercedes were however, later referred to the race stewards following their recovery of Rosberg's car in the opening practice session.

An FIA statement read: "During P1 at 10.28, members of the Mercedes AMG Petronas F1 Team covered the underside, rear, diffuser area and the front wing of car number 06 when it was brought back to the paddock after having stopped on the circuit due to a mechanical problem.

"As the car hasn't suffered any kind of accident damage this in my opinion is a breach of Article 27.4 of the 2015 Formula One Sporting Regulations and I am referring this matter to the stewards for their consideration."

First Practice:

1 Nico Rosberg (Ger) Mercedes 1min 34.274secs,

2 Lewis Hamilton (Gbr) Mercedes 1:34.344,

3 Max Verstappen (Nld) Toro Rosso 1:35.530,

4 Kimi Raikkonen (Fin) Ferrari 1:35.588,

5 Carlos Sainz Jnr (Spa) Toro Rosso 1:35.669,

6 Sebastian Vettel (Ger) Ferrari 1:35.739,

7 Daniel Ricciardo (Aus) Red Bull 1:35.818,

8 Daniil Kvyat (Rus) Red Bull 1:35.876,

9 Nico Hulkenberg (Ger) Force India 1:36.157,

10 Felipe Massa (Bra) Williams 1:36.469,

11 Felipe Nasr (Bra) Sauber 1:36.855,

12 Sergio Perez (Mex) Force India 1:36.889,

13 Susie Wolff (Gbr) Williams 1:37.242,

14 Jolyon Palmer (Gbr) Lotus 1:37.262,

15 Rafaelle Marciello (Ita) Sauber 1:37.372,

16 Pastor Maldonado (Ven) Lotus 1:38.080,

17 Fernando Alonso (Spa) McLaren 1:38.222,

18 Jenson Button (Gbr) McLaren 1:38.860,

19 Will Stevens (Gbr) Manor 1:38.981,

20 Roberto Merhi (Spa) Manor 1:40.477

PA