In the podcast Rusty's Garage, Barrichello announced that he had almost reached McLaren in 2010. "I would have been a teammate of Lewis [Hamilton]", says Barrichello. "I signed a contract with Williams around Spa in September 2009. Then McLaren came to me and asked for my services."
Out of loyalty to Williams, he cancelled the chance at McLaren. "The deal was good", says Barrichello. "I could have made more money. But I didn't do it. Williams was counting on me." From a sporting point of view, switching to Williams didn't seem the worst option anyway. McLaren had become champion with Hamilton in 2008, but did not play a role in the title fight in 2009.
Halfway through 2009 Williams was even ahead of McLaren in points in the World Cup. Barrichello's teammate at Brawn GP, Jenson Button, got the spot at McLaren in the end. Heikki Kovalainen had to leave the team there.