Bottas believes Ferrari is ahead of Mercedes so far in F1 testing

Ferrari's new SF90 has reliably featured at the top end of the timesheets throughout this week's first Barcelona test, as Sebastian Vettel headed the opening day and Charles Leclerc went quickest on the second.

In addition to the usual testing caveats over engine power and fuel loads, Ferrari's performances have been flattered by the fact reigning champion Mercedes has left it late in the week to run Pirelli's softer compound tyres.

But Lewis Hamilton said on Wednesday the Italian cars were looking "very, very strong", and team-mate Bottas went as far as suggesting Ferrari may have an initial edge.

"They do seem very strong," said Bottas. "No matter which kind of fuel load or engine mode they're running.

"We try to correct for that, but in any case they are quick. On short runs and long runs.

"I think we feel at this point they're a bit ahead, but obviously it's impossible to make detailed calculations."

Bottas stressed that Mercedes' results in testing did not matter to the team, as "we have our own references, and the timesheet is not the reference here".

"For sure we read something [into the times]," he said. "We look.

"But we really want to focus on the limited time of testing we have, we want to focus on ourselves and our package.

"I'm sure between the tests the teams will do a bit more analysing where we think we are. It really matters where we're going to be in Melbourne and that is down to how efficient we do these test sessions.

"Like I said before, Ferrari's looking very strong. There's no doubt about that."

Bottas added he expected Ferrari's strong start, coupled with the fact the W10 package does not yet feel fully optimised, to spur Mercedes on as it seeks to extend its five-year title-winning streak in F1.

"I feel a sense in the team, a bit of excitement to discover more about the car and really try to improve it," he said.

"At this point it looks like we're not miles ahead of anyone. It seems like Ferrari is, at this point, in a better place. I think it motivates us."

The Finn said he though the situation would change before the season opener as teams bring new parts, but says Mercedes cannot count solely on that to overhaul Ferrari.

"With the new rules, it's going to be a bit of a development race, we don't think anyone is going with this type of car in this test to the first race, including us," said Bottas.

"But we can't really rely on that, that it's going to be an upgrade, we do need still to try to make this spec of car better and quicker."