Sebastian Vettel has warned that Mercedes will be "quick no matter what" after Ferrari found themselves a lot closer to the front at Silverstone on Friday.
Nico Rosberg topped the timesheets for Merc in FP1 while Kimi Raikkonen was the fastest of the Ferraris in fourth place, but he was 1.314s slower than the German's time with Vettel was another 0.151s adrift in sixth spot.
Although Rosberg was again P1 in Free Practice 2, Raikkonen was just 0.347 behind in second place with Vettel another 0.020s off the pace.
"I don't know what happened to them," four-time World Champion Vettel is quoted as saying by Motorsport.com.
"I think you saw the pace in general of them in the long run and this morning, so they will be quick no matter what.
"Everything else will be a surprise, but if we can repeat it tomorrow, that will be good news."
Ferrari, though, had a trouble-free day, but Vettel insists they still have some work to do ahead of Sunday's British Grand Prix.
"We didn’t have any issues with the car and, more or less, we got through everything we wanted to do," he said.
"Still I’m not entirely happy with the car yet. Some of the things we tried were good and others were not so good. Now we have to make sure to have only the best things in the car tomorrow.
"Then I hope we can do a step forward. This track is a lot about finding the rhythm. About the tyres, I can say that it is only Friday, and not everybody was able to get everything out of both compounds.
"Anything can happen tomorrow and our main opponents will certainly be very strong, but if we can confirm today’s result, that would be good."