by Our Sports Desk

NICO ROSBERG clocked the fasted practice lap yesterday and hot favourite Lewis Hamilton warned of a tough battle with his fellow Mercedes driver ahead of the British Grand Prix.

The German scored a practice double, topping the time sheets in both sessions after a morning hydraulics failure threatened his outings.

But a lap time of one minute 34.155 seconds put him top of the pack with Ferrari’s Kimi Raikkonen in second and his teammate Sebastian Vettel in third, while Hamilton clocked in in fourth.

Two-time GP championship winner Hamilton heads into his home grand prix on Sunday with a 10-point lead over his teammate Rosberg, but the German is on form, having won three of the last four races.

However, Mercedes were reported to race stewards following the recovery of Rosberg’s car in the opening session.

An FIA statement read: “During practice one at 10.28am, members of the Mercedes team covered the underside, rear, diffuser area and the front wing of car six 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 our opinion is a breach of the regulations and I am referring this matter to the stewards for their consideration.”

Hamilton also had problems with his car, reporting over the team radio that it was “all over the place” and that he “couldn’t make it go any faster.”

And the 2014 BBC Sp orts Personality of the Year winner said ahead of the weekend’s race that beating Rosberg will be tough: “It is going to be a very hard weekend as Nico has been very quick.

“I can’t say who will be our main rival.

“It could be Williams or Ferrari. The weekend will be down to a good qualifying and extracting the most in the race.”

The young Brit blamed a poor start for his slip into second from pole position in the Austrian Grand Prix but explained that the problem has hopefully been rectified.

“The last couple of races I have had some ups and downs and last time the start made a huge difference,” added Hamilton.

“Nico simulated what happened for me, and found a serious issue that could have affected us perhaps this weekend, and that has now been rectified.”

However, when Rosberg was asked about the issue he joked: “I made it worse for him.”

Hamilton is expected to be cheered on by a crowd of 140,000 on Sunday.