Lewis Hamilton felt his Mercedes was "back to normal" yesterday in free practice but admitted the W08 still "weak" in many areas.
Hamilton and Mercedes have been mystified since the season kicked off by the car's difficulty to cope with its tyres, and mainly Pirelli's ultrasoft compound.
The team has made progress on that front however but Hamilton still ended FP2 0.215s off Kimi Raikkonen's fastets lap.
"The car feels back to normal, but it is still weak in a lot of areas," he said.
"The Ferrari is still the quickest and with everything that I'm currently pushing with, I can't beat the Ferrari's time.
"A two tenths margin is quite a good margin in that session. We'll see if we can improve the car overnight, but it looks like it will be a tenth or within a tenth.
"It's exciting, but positioning is everything because between the four of us it's going to be very difficult to overtake on Sunday."
Mercedes tech boss James Allison agreed with Hamilton's assessment about the difficulties in setting-up the W08 and achieving a good balance.
"We've got a car that has got many strong points but there is some trickiness to the way that it handles," Allison said in yesterday's media conference.
"That presents us with particular challenges when we are setting the thing up, but there is plenty we can do in the short-term, plenty we can do at each race and plenty we can do over the medium-term too.
"There has been a couple where Lewis had a tougher time. What he feels is a lack of grip in the car and what we see, and what we talk about afterwards, is that the grip is there but it's ever so easy to overstep it and pay quite a heavy penalty in lap time as a consequence.
"That experience that Lewis has had on a couple of occasions, Valtteri has had as well in a different direction in a different track.
"We have a situation where we have a car with a lot of performance that is able to compete in the front, but the window in which that performance is available is quite narrow and easy to step out of."
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