Fernando Alonso believes it is still too early to judge how strong Ferrari will be in the Japanese Grand Prix following Friday practice.
The Spaniard was fifth quickest in the afternoon session after posting the 11th fastest time in the morning.
Although Ferrari was competitive in the British Grand Prix at Silverstone - which is similar to Suzuka in terms of downforce requirements - Alonso admitted he remains unsure about his team's form for the weekend.
"Overall, the feeling is good and I don't think the high temperatures can constitute a problem for the tyres," the championship leader said.
"We have done a lot of races in hot conditions, and not that long ago either, given that Singapore was only a fortnight ago and just like we did there, we will have to learn to manage them, which indeed will be the case for everyone.
"It's hard to say if we can be as competitive here as in Silverstone: that was three months ago and we don't know exactly how our rivals' cars have evolved compared to how much progress we have made.
"We will have to wait until tomorrow, because usually on Saturday the pack gets jumbled up. As for the small updates we have brought here, there's not much to say and we will have to spend more time looking at their behaviour."
Felipe Massa, ninth fastest in the second session, echoed his team-mate's thoughts, although he is convinced there is still room for improvement.
"It's hard to say precisely where we are: what is certain is that many of our rivals seem to be competitive, but as usual, we must wait until tomorrow to get a clearer picture of the situation," Massa said.
"It won't be easy to decide what will be the best strategy. I'd describe the balance of the car as average: even if we didn't match the pace of the others, there is still a lot we can do to improve and we must also take into account the fact that the track changes a lot from one day to the next."