Mercedes has 'made improvements already' since F1 testing - Bottas

Mercedes introduced a major aerodynamic upgrade for the second week of testing at Barcelona but Bottas and world champion Lewis Hamilton felt the team still lagged behind Ferrari.

Hamilton said there were "no upgrades" for Mercedes for this weekend's Australian Grand Prix but both drivers said progress has been made in other ways.

"After two weeks of testing, the amount of data you have to analyse, to try to learn and improve is a lot," said Bottas.

"So it's been a very useful two weeks.

"As a team we have learned a lot about the package we had in testing, and how we can optimise it better for the first race.

"We have made improvements already, even though we haven't driven a single lap since testing.

"I'm confident we can be in a better shape.

"I'm sure every team has learned since testing, but it's only guessing at the minute."

Bottas said Mercedes faced a "big development race" until the end of the season and Hamilton reiterated his belief in testing that Ferrari is ahead.

Hamilton said Mercedes was not "talking BS [bullshit]" when it said it "had work to do".

"Everyone takes a step after testing," he warned.

"The car will be fresher here and we will have a much better understanding of it, but I think it's the same for everyone.

"And we didn't bring upgrades. It will be interesting to see how the Red Bull's upgrades work and for other people.

"Ferrari usually bring upgrades to the first race [too]."

Mercedes has arrived in Australia as the pre-season favourite every year since the V6 turbo-hybrid era began in 2014.

However, Ferrari has won the previous two Australian GPs.

Bottas said he would prefer to be more confident in Melbourne but believes being the less-favoured team has motivated his colleagues.

"Even though we don't feel like we are the quickest at the moment, there's good work ethic, motivation, everyone is looking forward to the season, we're looking forward to the fight," he said.

"When I was at the factory last week I could see people are really putting [in] a lot of effort and trying to make our package better with the tools we have.

"It's always impressive in this team to see that, and it's definitely a bit [of a] different feeling to previous years.

"Normally in testing we've been quite strong, and we've seen in the last couple of years here Ferrari being always strong.

"So, now we know as a fact they are going to be really strong, and we really need to improve if we want to beat them."