London, Mar 28 : Formula One champion Lewis Hamilton has admitted that his F1 world title defence was already in trouble.

The Brit, who finished 16th and 18th in early qualifying for tomorrow's opener in Australia, said: "We're clearly not in the place where we would love to be. But we're working extremely hard, as hard as we can."

"We've a steep, very tough challenge ahead of us but, if anyone can do it, I believe my McLaren team can. We've just got to remain positive and keep pushing," The Sun quoted Hamilton, as saying.

The new McLaren is proving far slower in corners than its rivals because it is not using a controversial "diffuser" which helps cars grip the track.

At one point yesterday, Hamilton was heard over the radio complaining about his car "bottoming out" and being "difficult to drive".

In contrast, flying Brit Jenson Button, fifth fastest in practice, has been told that he is as quick as Michael Schumacher.

Brawn GP teammate Rubens Barrichello, who spent six seasons with Schumacher at Ferrari, said: "Jenson is a super fast driver. On his day, he can be as fast as Michael." (ANI)