Jenson Button believes McLaren won't have it all their own way this weekend despite dominating Friday's sessions in Hungary.
The McLaren driver's team-mate set the pace in both practice sessions on Friday while Button was second in FP1 and then sixth quickest later in the afternoon.
The Brit revealed that a few "different things" attempted on in Practice Two did not go according to plan, prompting a return to the settings used earlier in the day.
"The first session was reasonably good - it's good to see that we're competitive straight out of the box," Button said.
"This afternoon's session we tried some different things to help the balance; I don't think it was the right thing to do so we've gone back on most of them."
"But I'm pretty happy with the car and I think we're reasonably competitive around here."
Button, though, concedes McLaren face a tough challenge this weekend as their rivals were not too far behind.
"The second session proved that a lot of people are quite competitive around here so it's going to be a fierce battle this weekend and from what we've heard it should be dry most of the weekend."