Nico Rosberg's Monaco Grand Prix triumph served notice Mercedes are a major force this campaign.

Story highlights

Nico Rosberg fastest in free practice ahead of the British Grand Prix

Mercedes driver edges out Red Bulls of Mark Webber and Sebastian Vettel

Home hope Lewis Hamilton fifth best at Silverstone

Rosberg won the Monaco Grand Prix earlier this season

CNN  — 

Mercedes occupied their usual position at the top of the practice time sheets Friday as Nico Rosberg recorded the quickest lap head of this weekend’s British Grand Prix.

The 28-year-old German, who won the Monaco Grand Prix earlier this season from pole, edged out the Red Bull pair of Mark Webber and three-time defending champion Sebastian Vettel in the second session at Silverstone.

His Mercedes teammate and crowd favorite Lewis Hamilton claimed the fifth best time in drying conditions after morning rain had rendered the first runs largely irrelevant.

Fellow Briton Paul Di Resta was fourth for Force India.

Rosberg’s time of one minute 32.248 seconds edged out Webber, who earlier this week announced he would be quitting Red Bull and F1 at the end of the season.

Read: Red Bull’s Webber to quit Formula One

Webber has claimed podium positions in his last four races on the track and once again showed his liking for its high speed straights and corners.

But Rosberg, who has headed the grid in three of the last four races, proved unstoppable again in the early sparring although he has some concerns for the weekend.

“Then the only question mark is our race speed. We practised for the race speed today. It seemed to be OK, decent, but I’m sure it’s still going to be a little bit of a problem for us,” he told AFP.

“The next thing is that it’s going to be another 10 degrees more tomorrow and Sunday and that could completely change the picture again.”

Vettel’s nearest challengers in this year’s title race, Ferrari’s Fernando Alonso and Kimi Raikkonen for Lotus were were 10th and 13th respectively.

Alonso’s teammate Felipe Massa again crashed out, damaging his front suspension, and ended with the 22nd fastest time.

2009 world champion and another home favorite, Jenson Button, was 11th best for the struggling McLaren outfit.

Saturday will see further practice ahead of final qualifying for Sunday’s race.