Lewis Hamilton impressed with Ferrari's gains from its new turbo

Ferrari used two engine development tokens for the update, taking its tally to 28 and leaving just four remaining, with engineering chief Jock Clear saying the changes "performed as expected".

Hamilton topped the times in second practice but Sebastian Vettel split the Mercedes and was just 0.257 seconds adrift of the reigning world champion.

"The Ferraris look very quick," said Hamilton. "They've got a new turbo so they've picked up their pace on the straights.

"Whether or not they've turned their engine up to test that, I'll assume they probably have, but we will see tomorrow.

"The Ferraris look quite quick and the Red Bulls will be quick also.

"Particularly with the Ferraris it looks like we might be very close with them.

"Hopefully we're going to have a bit of a race here."

Hamilton was impressive across both practice sessions but ran off track and even kissed the wall as he explored the limits.

"It's been a great day, you're not pushing hard enough if you don't go off the track, you'll never get near the limit if you don't go off the track," he said.

"I went off the track lots of times as I'm trying to discover the limit, trying to get as close to the limit to stay just above the limit.

"I was nearly in the wall several times, but fortunately I was able to stay out of it."

Rosberg was half-a-second adrift of his team-mate in third and admitted he was at a loss over his lack of pace.

"I need to understand if it's tyre temperatures or just me and driving lines or something like that. I need to understand that," he said.

"The long run was looking good, our car's looking good.

"The Ferraris seem pretty close but it's always so difficult on a Friday, you never knew what fuel levels they're running, how much engine power they're using.

"Red Bull had their engine turned down completely in the last session so they didn't show anything."