Mercedes sure it will stay with the Formula 1 frontrunners as Nico Rosberg gains on leaders

Despite a difficult start to the campaign with tyre problems in Australia and Malaysia, Rosberg has been the highest scoring driver from the Chinese Grand Prix onwards.

In the last four races he is the only driver to have started on the front row more than once, and more significantly he has cut a 35-point deficit to championship leader Fernando Alonso after Sepang to just 17 now.

And with new updates - including its carbon gearbox and rear suspension tweaks that Rosberg used for the first time in Monaco - having delivered a step forward in pace, the Brackley-based outfit is optimistic that it can keep up its progress.

"Making predictions does not make us quicker, so we need to focus and work on it, but the general trend seems to be the right one," Mercedes Benz motorsport boss Norbert Haug told AUTOSPORT.

"There will be ups and downs. But I think our curve is generally going up after a third of the season. This is not 'hurray, hurray, we can celebrate', it is just comparing last year to this year."

As well as Rosberg's pole position in China, Michael Schumacher set the fastest time in qualifying in Monaco last weekend, only to lose the front position because of a five-place grid penalty he was given for crashing into Bruno Senna in Spain.

Even so, the speed shown by the W03 as Rosberg finished right behind race-winner Mark Webber was evident, and it comes ahead of races like Canada and Valencia that should suit the characteristics of the car.

Haug says big lessons were learned from the tyre errors in the first two races, as Mercedes' drivers overheated their rubber in Australia and then could not generate enough heat in the Pirellis in Malaysia.

"We know we didn't get it completely right in the first two races, in fact we didn't get it right at all," he said. "But it is always like that if you are learning. If today was Australia or Malaysia we could have done a better job, and it was unfortunate for Nico to lose those points in Australia.

"He is 17 behind right now. It is not too bad. But it does not mean you are in a position to win the championship. However, we were fourth last year [in the constructors'] and if people would have said you will be missing just 17 points after six races then probably we would have brought it."