Button cautious despite quick start

Button was just pipped by the Renault of World Champion Fernando Alonso to the spot as the fastest 2006 car, but he was determined to keep his feet on the ground when talking about mounting expectations surrounding the team.

"At a test like this you know whether there are any serious problems, but you don't know how the car is going to be," he said. "We did a 1m16.5s and it was a couple of tenths off the Renaults, but we've only done 60 laps.

"We haven't been doing set-up work, we've just been putting laps on the car to see how reliable it is. We need the engine to be reliable and it's good to see that everything else is as well."

Despite his cautiousness about the opening day performance, Button admitted to being slightly optimistic about what he had found - as Honda Racing bid to put the troubles of their disappointing 2005 campaign behind them.

"It is only testing, but I'm happy with the way the car feels. It's definitely a step forward from last year's car, but we haven't pushed it as far as it will go.

"The engine's good, we've been very reliable all winter and also very strong in power department. We've been working all year on the driveability and been improving all the time.

"We're very well prepared for this season, more so than any other season. Two cars at the launch and a few tubs and many gearboxes and parts is exceptional. We're really on top of it."

But with the testing times so close at the moment, Button believes it was far too early to make any predictions about the overall form of the teams.

"We haven't got a clue who's going to be quick this year, there is no use trying to say who's going to be top. Hopefully we'll be challenging for wins but you just don't know, until we get to the first race."