Button and Hamilton wary on hopes

Jenson Button is cautious about discussing the prospect of winning back-to-back world titles having officially become a McLaren driver.

Button, whose McLaren contract started on 1 January, said he was "exhilarated" about joining Lewis Hamilton there.

"My aim is to keep the number one on my car for as long as possible but it is a little early to start talking about the world championship," he said.

Team-mate Hamilton said: "You can never take competitiveness for granted."

Hamilton, who is 25 on Thursday, said he had learned to be cautious following the team's poor start to 2009.

It's fantastic to be part of one of the most famous names in Formula 1 but it's also exhilarating World champion Jenson Button

McLaren's car was more than two seconds off the pace when it first ran last year, but the team recovered in the second half of the season and Hamilton won two races.

"Our common goal has to be to make MP4-25 a winning proposition as quickly as possible," he said.

"Only once we've achieved that can we start looking at winning races and then, eventually, the world championship."

Button, who will share the pre-season testing equally with Hamilton, said the time before the first race in Bahrain on 14 March was critical.

"The backbone of any title challenge is built on good preparation, hard word, focus and dedication," he said.

"The hard work starts here. The next 10 weeks could well largely dictate the destiny of the 2010 world championship, so it's crucial that we start testing very strongly and that we never let up.

Button has now officially started work as a McLaren driver

"I'm more motivated than ever to work with the team and my engineers, and I'm extremely positive for the year ahead."

McLaren's decision to pair Button and Hamilton is the first time a team has run the past two world champions.

But the two men have not met since Button was announced as a McLaren driver in November.

"We've both been to [the McLaren factory] for our seat fittings - but they were on different days," Hamilton said.

"The first time we'll start working together is later this month, when we'll both be at Woking together, then we'll have the launch and the first test.

"We'll be sharing the pre-season testing equally, and it will be important to keep a crossover of information between us to make sure we are both pulling in the right direction."

Button, who joins McLaren after seven years with the same team as it morphed through different guises as BAR, Honda and Brawn, added: "It's fantastic to be part of one of the most famous names in Formula 1.

606: DEBATE God I'm looking forward to 2010 wils333

"But it's also exhilarating: I'd been at the same team for seven years so this is a big cultural change for me, and something that I'm really looking forward to.

"There are a lot of new faces to remember and lots of names to learn - and that's all got to be done alongside the engineering and limited testing we have ahead of the 2010 season.

"But I'm loving every minute of it - the atmosphere within the team feels fantastic, and I've already started to feel at home here. I can't wait to get out in the fantastic new car the team has built for me!"

McLaren will run their new car for the first time on 1 February at Valencia, where many of the top teams are expected to have their 2010 models.

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