Mercedes has said that despite an encouraging winter testing, it still does not know where it stands in relation to its rivals.

Speaking ahead of next week's Australian Grand Prix, Nico Rosberg commented that only when the cars take to the track for the first time on Friday, then the Mercedes team will be able to see where it stands in the 2013 Formula 1 pecking order.

"The first Grand Prix is where everyone finds out where they really are and we can judge how well we have done against our competition," he said, "as the times in winter testing just don't tell the full story."

He also added that the unusually cold conditions in testing did not provide the team with a fair indicator of how its 2013 car treats its tyres in warm conditions and expects tyre degradation to be its biggest test: a characteristic that plagued the team's 2012 car, the W03.

"The weather in Melbourne looks very hot at the moment which is going to be a tough challenge as we have no experience with the F1 W04 in those conditions," he continued. "Tyre degradation will be the biggest issue for everyone so we need to look at that carefully and do a good job in managing it."

Mercedes motorsport head Toto Wolff also played down the impressive pace shown by his team over the winter and underlined that the higher temperatures in Melbourne are a step into the unknown for the Brackley based outfit.

"When it comes to starting a new season, it's only facts that count - everything else is simply speculation," he stressed. "The facts are that we had a good winter test programme, completed the second highest mileage of any team and made some good progress.

"[But] we know, too, that we will be running in very different temperatures, on a different track surface and that every team will have to finally lay their cards on the table in qualifying on Saturday.

"Only then can we have a first indication of where we stand in terms of performance."

By George East