Valtteri Bottas claims Mercedes has "made improvements" since their outing in Barcelona two weeks ago. The Finn makes this claim despite Hamilton suggesting the German team haven't got any upgrades on the W10.
Mercedes didn't trouble the top of the timesheets in Barcelona and left Ferrari to pick up the faster lap time. Mercedes do have a tendency to hold everything back until Q3 on Saturday.
The Silver Arrows managed to complete a high mileage, and Bottas says the data collected has been useful for preparations.
"After two weeks of testing, the amount of data you have to analyse, to try to learn and improve is a lot. So it's been a very useful two weeks," Bottas told Autosport.
"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."
Ferrari, who has won the last two Australian Grands Prix, is favourites for the race win again in 2019. But Bottas claims it's things like that which help spur Mercedes on as they strive for improvement.
"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 added.