McLaren 'not there yet' on car set-up in Barcelona F1 testing

Last week's first test started well but ended with Button and team-mate Fernando Alonso turning just nine laps of Circuit de Catalunya over the final day-and-a-half.

Both drivers suffered minor problems on the first and second day of this week's second test, but with Honda's upgraded power unit proving reliable, the focus can turn to car set-up.

"There's still a lot of work to be done over the next two days to find a set-up that really works for us, because we're not there," Button said after completing 121 laps on Wednesday.

"I don't feel we've really done any proper testing with the car yet, in terms of set-up work.

"It's been mostly aero work, and understanding if we're in the right place or not.

"There hasn't been any specific driver set-up work.

"The next two days are very important for us to fine-tune the car and find a balance that really works.

"We're not there yet, we need two really good days to feel ready for Melbourne."

Button said McLaren had planned to focus on car set-up on Wednesday afternoon, only for windy conditions to wreak havoc with the handling.

"This afternoon the aim was to focus on that, but with the wind today it's been really difficult to do any proper running," Button added.

"I was struggling, I was talking a lot with my engineers about the balance on the radio, not feeling good, hoping it wasn't just us.

"It wasn't, a lot of people struggled - even on soft or super-soft tyres, the times weren't what we expected. That was a good thing.

"I'm quite happy about that, because it wasn't looking so good."