Never ones to miss an opportunity to play down their chances, keen to play the underdog card at every given opportunity - despite the titles and the unrivalled dominance of the hybrid era - Mercedes has suggested that Ferrari has taken a leaf out of its book.

At a time Ferrari boss, Mattia Binotto was all doom and gloom, telling reporters that the SF1000 doesn't have the pace of its predecessor, and suggesting that his team won't be truly competitive until much later in the season, in an article entitled "What we've learned from testing", Mercedes suggested that all is not what it seems.

"What can we say about the leaderboard after three days?" writes the German team. "This is where life gets tricky because all these estimates are lower bound estimates.

"You can say with some confidence that your competitors are 'at least as fast as X'," it continues, "but you do not know for sure how much faster they could have gone.

"No-one wants the egg on their face of claiming that they are faster than another team, because they can never know for certain what was hidden or what is coming next.

"For example, will Red Bull bring a significant upgrade package to the second test? Why have Ferrari spent this test running their PU consistently at much lower levels than their partner teams?"

Though we have yet to see either Ferrari driver on the C5 rubber on which Lewis Hamilton and Valtteri Bottas posted their timetable topping times on Friday, Vettel has run the C4, though he was 2.4s off Mercedes C5 pace.

However, Ferrari customer team, Alfa Romeo has run the C5s, with Kimi Raikkonen's best time 1.3s off Bottas' best and Antonio Giovinazzi 1.7s down on the Finn.

Through the speed-traps, certainly on the first two days of testing, the Ferrari was significantly slower than the Alfa, and it was shortly after Vettel ramped up proceedings on Friday his engine failed.

Having dominated testing last year, only to fall apart once the season got underway, Ferrari admits that it has changed its approach to testing this year.

"We changed the approach to testing and the programme," said Binotto. "We focused the first session, so all three days, in trying to map the car in various aero configurations, various mechanical configurations, without really trying to optimise the set-up and look for overall performance.

"Some of the others are faster than us at the moment," he continued, "how much faster is really difficult to judge and I will go through all the data in the next few days. But I don't think we are as fast as them at the moment.

"Do we have any concerns?" he continued. "Certainly, yes, when you are not as fast as you would like to be, but I think it is too early to define it and understand it.

"We should not forget the history of last year," he added. "Let's wait until next week and wait for Australia to better understand the true picture."

Speaking on Friday, Vettel admitted that, like Red Bull, Ferrari has yet to show its hand.

"You can play around a lot with engine modes, etc," he said, "but I think right now the target is not to prove the maximum power of the engine, the target is to do as many laps as possible.

"Ramping up the engine and so on, is probably not something you want to do in testing and certainly not to show everyone. It's not on the agenda as far as I know."