Sebastian Vettel expects the Mercedes team to up its pace on Saturday after Ferrari was close to the German squad in Friday practice for the British Grand Prix.
Kimi Raikkonen was second quickest in second practice, with Vettel finishing third, both men around three tenths of a second behind pace-setter Nico Rosberg.
"I don't know what happened to them," said Vettel. "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," said Vettel.
"Everything else will be a surprise, but if we can repeat it tomorrow, that will be good news."
Vettel says he was pleased with Ferrari's progress at Silverstone today.
"I think we didn't have any issues with the car," said the German. "And more or less got through everything that we wanted to do.
"I'm not entirely happy yet with how the car feels, but I think for tomorrow we can make a step forward.
"I think we can improve. We tried a couple of things, now we have to find out what was good or what was bad, and put all the good things in the car for tomorrow.
"We didn't have anything going wrong with the car. This track is a lot about finding the rhythm, so it was good to do a couple of laps."