McLaren's Lewis Hamilton remains cautious following practice for the Chinese Grand Prix on Friday even though he did finish the day with the fastest time.
Hamilton ran strongly in both practice sessions, setting the third best time in FP1, before moving to the top of the timesheets in FP2, when he posted a 1 minute 35.217 seconds.
He eventually ended the day 0.248 seconds up on Nico Rosberg's Mercedes, who was second, and 0.376 seconds up on his team-mate, Jenson Button, who was third and who had been quickest in first free practice.
"We may have topped the timesheets in each session, but I don't necessarily think today's times make us the favourites for this race," Hamilton said. "The car does feel good, but our pace looks pretty similar to some of the other cars on long runs.
"Everyone talks about us having a straight-line advantage, but that's not true – other cars have the same speed as us at the end of the straight. We're a little bit quicker than some teams, but, equally, they're able to run more downforce. It's about getting a good balance."
Despite his reservations though, Hamilton did add that he is happy with the MP4-25 and that his aim now is to ensure he qualifies as high up as possible.
"We're continuing with the good feeling we felt in Malaysia. We've made some further subtle changes and they were encouraging. I come out of today with a positive feeling. We've got to keep our heads down now and concentrate on gaining a strong qualifying position tomorrow," he continued.
Team-mate Jenson Button meanwhile was similarly guarded, even if his pace also appeared very competitive.
"We're moving in the right direction. There are a few things we can still tweak over the course of this evening, but I think we've come here with a pretty good car from lap one," Button added. "Of course, some of the teams haven't shown their hand yet, but you can tell from the long-run times that they're competitive.
"Maybe we're not on their pace yet, but we've got tonight to make further improvements to the car.
"Overall today's been good. This afternoon was a little frustrating: on my new-tyre run I ran into traffic – which you seem to get in every session – but the actual work we've done, and the direction we've taken, has been positive. There are a few more things we need to do, but we're almost getting the maximum out of the car – especially on the long runs."