F1 testing: Ferrari surprise performer at Barcelona, says McLaren

While Mercedes has been the pacesetter so far, Ferrari's strong form - which included Kimi Raikkonen topping the second day - has lifted hopes that it can bounce back from a disappointing 2016 F1 campaign.

McLaren racing director Eric Boullier says Ferrari's form is the one that has caught his eye, even though his own focus has been on the troubled star for Honda's new engine.

Asked where he saw the performance of McLaren's rivals, Boullier quipped: "A little bit faster than us...

"Obviously it is difficult to say, because you don't know the level of fuel, you don't know especially the engine, how many switch downs you are on the power curve, obviously.

"But if I may say so, the Ferrari is surprising and people were not expecting Ferrari to be matching Mercedes' lap times.

"Red Bull are a bit down, but you never know the fuel level.

"Everybody has got their own secrets, everybody is changing their plans, so even between teams we tried to find out and sort out who is doing what. It is not easy.

"Next week's test will be a little bit more revealing about performance, but definitely we have to wait until Australia."

While Honda's disappointing start with its new power unit has marred McLaren's week, Boullier said there were encouraging signs from the performance of the MCL32 chassis, which he described as "pretty good, actually".

Fernando Alonso set McLaren's best time of the week so far on Wednesday, a 1m22.598s on the ultra-softs, 2.893 seconds slower than Mercedes' Valtteri Bottas managed on the same compound.

"I think obviously in any kind of world, even the perfect car, when you push the car to the limit you will always have understeer, oversteer, or something like this," Boullier said.

"But I guess at least for the chassis, both drivers doesn't complain and feel that the base of the chassis is good.

"There will be a high development rate, especially for the beginning of the season especially.

"I expect most of the teams to bring nearly a new car in Australia already, so at least the base is good, the platform is good and we can develop around this which is good."