Frenchman Sebastien Loeb can secure his fourth world rally championship in a row in Britain on Sunday and dash Marcus Gronholm's hopes of heading into retirement with a third title of his own.
Citroen's Loeb leads the Finnish Ford driver, who was champion in 2000 and 2002 with Peugeot, by six points going into the final round of the season.
Gronholm, whose team have clinched the manufacturers' championship for the second year running, needs to win in Cardiff and hope that his French rival fails to finish in the top five.
That is unlikely, even if Loeb has failed to finish on three occasions so far this year.
The most Gronholm can do is point to the example of compatriot Kimi Raikkonen, the Ferrari driver who wiped out a 17-point deficit with two races remaining to win this year's F1 title by a single point.
"It will be difficult to win the title but I have a chance," the 39-year-old Gronholm, who won in Britain last year and in 2001, said in a statement.
"What happened in F1 is a good example... that's a big spur for me because for Finland to win both the F1 and the WRC titles would be something special.
"I don't feel under pressure because it is out of my hands now," added Gronholm, who crashed out of the previous round in Ireland while Loeb won.
"This is my 150th WRC start so it would be great to mark that and my last rally with a victory. But it's the title I'm thinking about."
By Sunday evening, Loeb should have joined Finland's Tommi Makinen (1996, 1997, 1998 and 1999) in the record books as the only drivers to win four titles in a row.
Loeb will be taking no chances in what will also be a farewell to retiring Citroen team boss Guy Frequelin.
"We lead by six points so we won't need to win at all costs," said the champion, who has 110 points to Gronholm's 104, in a team preview.
"I don't enjoy driving to finish but, given the importance of the stakes, it's logical."
The rally, a classic test in the muddy forest tracks of south Wales, throws fog, rain and ice at the drivers and this year they have to contend with a return to night stages today and tomorrow as well.