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Valtteri Bottas is poised to be confirmed as Lewis Hamilton's team-mate at Mercedes for next season ahead of this weekend's Belgian Grand Prix.
The Finn, who turned 30 on Wednesday, has seen off the team's French reserve driver Esteban Ocon, and British rookie George Russell, to get the nod alongside Hamilton for 2020.
Team principal Toto Wolff has decided to take up the option on keeping Bottas for a fourth consecutive season.
The PA news agency understands an announcement could be made by Mercedes as early as Thursday ahead of Bottas' appearance in the official press conference to preview Formula One's return to action following the summer break.
Mathematically, Bottas is Hamilton's closest challenger for a sixth world championship, having won twice this year.
But the former Williams driver is 62 points behind his team-mate with only nine rounds remaining. His second place in the championship is also under threat from Red Bull's Max Verstappen following the Dutchman's impressive campaign.
Bottas last tasted victory at the Azerbaijan Grand Prix in April, and failed to take advantage of Hamilton's poor showing at last month's rain-hit German Grand Prix when he crashed out.
He then finished a disappointing eighth at the last round before the summer break in Hungary following contact with Ferrari's Charles Leclerc.
But the inoffensive Finn provides stability at Mercedes following Hamilton's fractious relationship with former team-mate Nico Rosberg. The all-conquering Silver Arrows also remain on course to become the first team to win six consecutive drivers' and constructors' championships this year.
Russell, the 21-year-old British driver, is on the books at Mercedes, and hoped to be in contention to partner Hamilton next year following the impressive start to his grand prix career for Williams.
But Wolff ended Russell's hopes of a drive when he admitted that an early promotion could thwart, rather than hinder, his progress.
The season resumes in Spa-Francorchamps on Sunday, with Hamilton looking to edge closer towards a sixth world championship which would move him to within one of Michael Schumacher's record.
