Ferrari is bluffing, says Hamilton

Sebastian Vettel led the way on the penultimate day of F1 testing with the fastest time of the two weeks so far, despite visibly sandbagging during the morning session with ultrasoft tyres fitted.

It is the third of the seven completed days that have been led by a Ferrari driver, following two for Kimi Raikkonen in the opening week, while Hamilton has topped one and Mercedes teammate Valtteri Bottas two.

Vettel rejected the suggestion Ferrari is the favourite for the 2017 season, and Hamilton believes its tactics made it tough to know its full potential.

"I think Ferrari are bluffing and that they are a lot quicker than they are showing," he said. "They're very close to us. It's difficult right now to say exactly who is quicker.

"But they are very close, if not faster. Whatever the case, I can't wait to go out and compete. Just a couple more weeks to go."

Mercedes non-executive director Niki Lauda conceded on Thursday the champion team has not hit targets with all of its upgrades for the W08 so far.

Hamilton finished the day second fastest, 0.328 seconds off Vettel's benchmark on the same compound, while Bottas was eighth following his afternoon focused on long runs.

"It was good to get some laps in this morning with slightly lower fuel," Hamilton said. "We worked on balance and made quite a few changes. I learned a lot about the car before handing over to Valtteri.

"We were trying to simulate something a bit more like qualifying and the car felt good on lower fuel. It's great to feel it come together."

Bottas: Mercedes not relaxing

Mercedes has dominated F1 since the turbo-hybrid engine formula was introduced in 2014, with Ferrari's expected challenge last year failing to materialise.

Asked if Mercedes remained favourites two weeks out from the season opener, Bottas admitted it was "very difficult to say".

"We are definitely not confident that we are in the front," he said. "We are not kind of, relaxing or being in a comfortable situation at all.

"I think we do feel the other teams have made good progress over the winter, I think Ferrari is looking very strong, Red Bull can always surprise, even some other teams can be close.

"Definitely some other teams like Ferrari, they are looking very solid and strong and fast - and who knows what people, are bringing to Melbourne. So we are aware that we should not underestimate them and we're not at this point saying that 'OK, we're the number one'."