Rosberg laments 'disastrous' Friday

The German and team-mate Kazuki Nakajima struggled with a lack of rear-end grip throughout the day, and despite being bullish on his chances of fighting for a podium before practice started, Rosberg is now hoping for a significant improvement overnight to re-emerge as a points contender.

His fastest time was 1.159secs off pace-setter Lewis Hamilton's McLaren, with Nakajima setting a mark four tenths of a second quicker.

"Today was a real disaster for us, so I'm hoping that tomorrow will be better," said Rosberg. "We're going to have to work very hard tonight to try and improve things.

"We had really low grip, especially at the rear. It was really very poor."

Rosberg, like many of his rival drivers, found that the option Bridgestone tyre was harder to get into the optimum temperature range, setting his best time on the medium-compound primes.

"To be honest, there was not much difference in the tyres," said Rosberg. "The option was a little bit more difficult to get up to temperature today, so the prime was a little bit quicker. We will see tomorrow, it might be different again."

Rosberg admitted that although fighting for a podium is a target, he is focusing more on helping Williams climb from its current position of fifth in the Constructors' Championship.

"A podium would be nice, but it's difficult. Especially because McLaren has made such a big step," said Rosberg. "So a podium is not so important - what really counts is championship position."