Formula One champion Jenson Button's move to McLaren is shaping up to be one of the most intriguing decisions of the season. Button left constructors' champion Brawn GP in November after seven years with the former Honda group just before it was taken over by Mercedes, which is investing in an F1 team for the first time in 55 years. The Briton traded in the comforts of a team he knew well for a chance to drive at McLaren, where teammate Lewis Hamilton has been racing since he was 13. Hamilton's influence inside the team led Fernando Alonso, who joined immediately after winning a second straight championship in 2006, to leave after just one season due to supposed favoritism. “Jenson knew exactly what he was letting himself in for,” McLaren team principal Martin Whitmarsh said of his all-British lineup. “So far he hasn't regretted it. We will see as the season unfolds which of our drivers feels most uncomfortable – inevitably they will. One of them has to feel uncomfortable if he's being beaten by the other.” Last season, Button won six of the first seven races and then hung on to win the championship over Red Bull driver Sebastian Vettel. Hamilton was fifth after a mixed season with McLaren, but preseason testing has shown that the British team is one of the favorites going into a field where Alonso has been reinvigorated by a move to Ferrari and seven-time champion Michael Schumacher returns to take Button's place. Despite all of the competition on the grid, it's the in-house threat that seems most dangerous. “Our chances are good. I have a confidence in my ability and my confidence in building a good team around me,” Button said. “But you never know until you're racing someone in the team. It's very difficult to know where you stand. “There will be rivalry, there always has to be between teammates. (And) one of us is always going to be on top.” Whitmarsh, who regrets how the team treated Alonso, said the rivalry will help the team's drive for the title. Hamilton said his working relationship with Button was good, but the 2008 champion did not mince words when it came to getting back into the title fight. “I'm happy to put my hands up and say when I've been beaten, and I have lost a race to a teammate, but not a championship,” said Hamilton, who also admitted to errors in handling Alonso's stay at the team. Button said his driving style will also suit new regulations, which have banned refueling.