Jenson Button hoping for a pleasant surprise in Melbourne

Jenson Button is hoping for a 'pleasant surprise' when he gets into his rejigged McLaren at the season-opening Australian Grand Prix this week after reliability problems hampered his pre-season testing.

Admitting that he had nowhere near enough time in testing, the 2009 world champion said he admired the aggressive approach McLaren had taken by making major alterations to the car, even if that meant he had no idea how fast it would go.

"You would say that Ferrari and Red Bull have dominated testing with their pace and reliability and they are probably the happiest coming out of winter testing," the 31-year-old Briton told reporters on Thursday.

"Our pace? I really don't know where we are, which is exciting in one way because we could be pleasantly surprised this weekend."

Button, who won in the rain at Albert Park last year and will be going for a third successive victory in Melbourne on Sunday, said that precedent helped his optimistic outlook.

"We didn't come here with the quickest car last year but we won the race," he said. "It was tricky circumstances with the weather but we still won the race.

"I'm hoping that we can wheel the car out on Saturday for qualifying and be as quick as the quickest. I might be dreaming but you've got to be positive.

"With the new exhaust system and a few other tweaks in the car we have hopefully made up quite a bit of ground," he added.

"Whether it's enough to really challenge the top teams, we'll have to wait and see."

Button also had limited time to test his car in 2009 with the new Brawn team but he raced to victory from pole position in the season-opening race at Albert Park on his way to claiming the title.

"I'm not going to lie, the amount of laps we did in testing was not enough," Button said. "We did about half of what the top guys did, it's nowhere near enough going in to the start of the season but I have been there before and I won the championship.

"Everything is possible."