Mercedes now 'on the up' - Rosberg

Mercedes GP had decided to hold back on a major update package for its W02 until this week's final test at Barcelona - and that meant it was unable to show its full potential in earlier tests.

That strategy meant the team faced its dramas during early running, but it made big progress over the second half of the last Barcelona test - prior to introducing a major revamp of its car for this weekend's final outing.

And with Michael Schumacher having topped the timesheets on Friday with the updates - which included a new diffuser, exhaust layout, wings and bodywork - hopes are high that the team is now in a position to build on its form last year.

"Definitely the team has made a lot of progress, so it has been great to see how much progress has come on," said Rosberg at the conclusion of testing on Saturday.

"Of course we are not there yet, as we want to win the world championship and we are not the fastest car yet, but things are going in the right direction so that is really nice to see."

Rosberg believes that the team has regained its momentum in the last two tests - after a tough time in the early spell of its winter preparations.

"We are on the up for sure," he said. "It has been a much more difficult winter than we anticipated, although it was always going to be that we would not be quick in the beginning.

"But still, it was more difficult and it has been great to see how the team turned things around and pushed on with the new upgrades and everything.

"The team managed to get them on the car and working as expected - which is also a bit different to last year where very often things they got on the car weren't working as expected.

"The theory says that it is going to be 0.4 seconds quicker, you put it on, generally there are very few issues with them and they are 0.4 seconds quicker. So that is nice to see."

Despite being hopeful that Mercedes GP now has the platform to improve on its 2010 campaign, Rosberg does not believe the team is a match for pre-season favourite Red Bull Racing.

"I think there is one team that is clear ahead and that is not us at the moment - but I may be wrong," he said. "We expect that we are better than last year and that is the main thing."