Felipe Massa thinks Thursday was the best day of Williams' winter testing so far but is still refusing to predict the team's place in the pecking order.
Massa finished the penultimate day at the Circuit de Catalunya second behind Kimi Raikkonen, though his quickest time was set on soft tyre to the Ferrari's ultra-soft. The Williams driver completed 119 laps and says the car feels "positive" in both long and short runs.
"I think it was good," he said. "Actually it was quite good, I think it was the best day up to now. We didn't have an amazing week last week, I would say, but this week is going very well. It was quite good for Valtteri and today was a very good day for me to understand the car. That's the most important thing, so I managed to understand the car in the best way compared to last week.
"Changing the set-up, the behaviour of the car, the feeling of the car was positive. Also trying the programme we did, on the long runs the car behaved well, but also on the short runs I could have done even a slightly better lap time because I had traffic with my ultra-soft tyres. But I think it was positive, so I am happy with the day and I hope I can be happy tomorrow as well and I hope we can be 100 percent ready to start the season."
Despite his positive mood, Massa remained coy on Williams' chances this year, saying: "Where we are is difficult to say, but I think we can be competitive and we know Mercedes is at the front, maybe Ferrari is there but then I think maybe can be many other teams with a small difference in terms of lap time, but I hope we can be there in a good fight. But we will know at the first race anyway."
Williams has targeted an improvement in slow-speed corners this year, a weakness that has plagued its last two Formula One cars. Though there is room for improvement Massa has seen definite progress through Barcelona's slow final sector.
"Sector three we still need to improve. For sure it was the weakest point of our car last year and we know that we are still not having the best car in that sector but I think the car is better than last year. So it was definitely a better feeling - the new car in slow corners - than last year.
"We know we still need to keep improving, keep working from where we did from the middle of the season until now to improve especially that area. But I think it was a good day, I think the reaction of the car was positive today. It was the best day I had compared to last week."
Massa returns to the car on Friday, the final day of testing for the teams until the Australian Grand Prix weekend commences in two weeks' time.