Silverstone: Nico Rosberg stamped his authority on Friday`s preparations for this weekend`s British Grand Prix by clocking the fastest time in both free practice sessions while Mercedes team-mate Lewis Hamilton struggled to find any rhythm.
The 30-year-old German clocked a best time of one minute and 34.155 seconds on Friday to wind up three-tenths of a second ahead of the two Ferraris of Finn Kimi Raikkonen and four-time champion German Sebastian Vettel.
Hamilton was a further tenth of a second adrift back in fourth after a ragged day that saw him fighting for balance and pace in a gusty wind and intermittent hot conditions in front of his home fans at Silverstone.
The series leader and defending two-time champion had struggled to match Rosberg, who overcame a loss of hydraulics during the morning, throughout the day.
"The car`s all over the place - I can`t go any faster than I am right now," a frustrated Hamilton told the team with 15 minutes remaining.
Despite his success, Rosberg was also unhappy with his car`s handling on a puzzling day for a team that appeared to be in supreme form again.
"No, I`m not that happy," he said.
"The car was all over the place still. I think it was the track out there that was really difficult, especially as it is a lot hotter now than it will be on Sunday for the race.
"So we need to be careful with that. The balance that was good today will not be good for Sunday so that is where the difficulties come in -- and you have to really think ahead, but I think it was valuable today and I learned a lot of things."
Hamilton, who leads Rosberg by 10 points in the championship after eight of this year`s 19 races, was clearly less than satisfied at being nearly half a second off the pace.
Asked how much performance he felt he had to come, on Saturday, he responded: "Hopefully, a lot.... Because if there isn`t a lot, we are in trouble. It hasn`t been the easiest of days, but it has generally been ok. The long-run pace was not so great. We have a bit of work to do on the set-up.
"I have to sit down and work out where it is. I think it is a general balance thing that we have to get right."
The woeful form of the two McLaren-Hondas of former world champions Spaniard Fernando Alonso and Briton Jenson Button showed no signs of an upturn in fortunes as they finished 15th and 17th respectively.
The session was twice interrupted by red flags, when Frenchman Romain Grosjean of Lotus and later Spaniard Roberto Merhi of Manor lost control and went off at Luffield, a corner that also claimed Alonso who ran off at the same place.
Nobody was injured in any of these off-track excursions on a day when Rosberg`s meticulous approach to his job paid dividends in difficult, hot and testing conditions, the air temperature hovering around 24 degrees Celsius and the track touching 40 degrees.
Thirty years on from his father Keke`s stunning feat in clocking one of the fastest laps of all time in qualifying for the 1985 British event - his lap at an average speed of 160 mph stood as the record, anywhere, for 17 years - Rosberg was dominant on Friday.
He and Mercedes were the focus of the day, even when he pulled off and stopped with a loss of hydraulic pressure during the morning, a pause that led to an official reprimand for his team, when they covered the car to transfer it back to the pits.
The team were summoned to see the stewards before second free practice to explain and told they had broken the rules. Cars may only be covered following an accident. The reprimand followed.