Rosberg encouraged by progress

The Williams driver finished 2.3 seconds off the pace in the morning, but bounced back thanks to a new set-up in the afternoon, where he posted the sixth fastest time, less than a second off the top.

Rosberg admitted he was pleased with the progress, but said he will still need more speed for tomorrow.

"The morning didn't start too well and we weren't looking so good, so we made some big set-up changes over lunch and we definitely improved and found some clear direction," said Rosberg.

"We have some new development parts on the car, which have helped our pace even if the conditions have been too variable to really get the most out of them today.

"If I think about it, our experience today has been much like last year when we struggled here on Friday but improved a lot over the course of the weekend.

"So we have taken some good steps forward today, but of course we still need to find some more performance tomorrow to close up to those in front of us."

Teammate Kazuki Nakajima, in contrast, had a more difficult second session after struggling for grip.

The Japanese wound up 15th.

"In the morning, conditions weren't too bad, even if we had to improve our laptimes considerably," Nakajima said. "We made some set-up changes, but I found this afternoon was much trickier.

"I was struggling to get a good feeling from the car. I'll be looking to find overall grip in tomorrow's practice session, and if I manage to do this, then I will be able to push more."