Rosberg hails Williams' progress

Rosberg made good use of the improvements to move to the top of the times in second practice at the Barcelona circuit.

Team-mate Kazuki Nakajima was second quickest.

The German driver reckons Williams has gained at least a few tenths a lap thanks to the updates.

"Today was our first run with the new aero components on the car and they all seemed to work well," said Rosberg. "They're giving us a few tenths extra per lap so we've made definite progress.

"Everyone has brought new developments here though so we will see how things look in qualifying. We also ran some tyre compares today.

"It's not obvious which direction will be the right one, so strategy is going to be very important and will have a major impact on the race."

Nakajima was also pleased with the new components, despite having problems with his tyres.

"We had a pretty good day and it seems that all the updates are working well," he said. "I found it quite difficult to get enough grip with the hard tyre, the soft one definitely has the advantage for me. We now need to focus our attention on qualifying well tomorrow.