Jenson Button is expected to be announced as a McLaren driver later today after signing a three-year deal to partner Lewis Hamilton at the team.
The reigning world champion is believed to have accepted a move to the Woking team after failing to agree terms to remain at the former Brawn GP team, which is being rebranded Mercedes Grand Prix next season.
Button's move will ensure that McLaren will carry the prestigious number one for a second successive season.
Mercedes team principal Ross Brawn told The Independent newspaper today that remaining with the team that took him to the 2009 world championship would be "logical", but Button's management is understood to regard a move to McLaren as the best long-term option.
"His best future is with our team, where he has a good group around him, and there's a lot to be said for that," said Brawn. "The logical thing would be for him to stay with us, but of course logic doesn't always prevail."
McLaren had been close to signing Kimi Raikkonen, but negotiations broke down last week over contract terms, with the salary offered some way off what the Finn's management was seeking.
It is understood that disagreement over ancillary contractual factors such as sponsor appearances and the freedom to contest rallies also played a role.
Raikkonen is now set to take a sabbatical from Formula 1, with a World Rally Championship campaign a possibility prior to a possible return in 2011.