BAR have confirmed that Takumo Sato will replace former world champion Jacques Villeneuve as Jenson Button's team-mate next season.
Villeneuve has been with BAR since its inception in 1999, although that time has been marked by a series of disappointments and the Canadian has long been tipped to lose his seat for 2004.
Sato, who made his grand prix debut at Jordan in 2002, has been named as his replacement after spending this season as BAR's official test driver.
Sato, the 2001 British Formula Three champion, has the backing of engine manufacturer Honda, who were keen to see a Japanese driver given his chance in Formula One.
That has left Villeneuve out in the cold, with the former Indianapolis 500 winner almost certain to lose out on a drive for 2004.
There are no vacancies in Formula One's top four teams, while a season with the likes of Jordan or Minardi is unlikely to appeal, especially as he would have to take a massive pay cut.
That leaves the second seat at Jaguar, which is not expected to tempt either party, while Sauber have yet to confirm their second driver, although Felipe Massa seems certain to return.
A return to Champ Car racing in the United States is a possibility, with Villeneuve's manager and former BAR boss Craig Pollock now a team owner, although such a move was played down earlier in the season.
Villeneuve is most likely to take a year out of Formula One and hope to find a drive in 2005.