Mercedes motorsport boss Toto Wolff has "dampened" expectations ahead of the new season despite Merc's impressive showing in testing.
Nico Rosberg posted the fastest time at Barcelona this season during the final day on Sunday while team-mate Lewis Hamilton claimed P1 on two of the other three days.
Many are now tipping the Brackley squad to spring a surprise or two in Melbourne, but Wolff warns against getting carried away.
"I have to dampen them because they are quite simply not realistic," he told German news agency dpa.
"It is of course pleasant to be at the front in testing but it means nothing."
He added: "It is perhaps a cliché but test drives and races are two different things, and we are there to race.
"I don't think you can interpret too much into the test results. It was incredibly cold here and the teams drove with different fuel loads.
"You could theoretically deduce if a car is right or not. The truth is though you can't see anything. (World Champions) Red Bull for example showed nothing. We won't know until Melbourne what's really going on."
Teams are often accused of sandbagging or trying to grab headlines by running low fuel loads in testing, but Wolff says they were going according to their plan.
"We worked out our plan and drive what we wanted, but not to impress anyone or to bluff," he said.