Japanese Grand Prix in 90 seconds
By Martin Brundle
BBC F1 analyst
Needing only a fifth place or better in the last two races to clinch the world title suggests Jenson Button should comfortably take it now. Having said that, even fifth has looked unlikely over these past weeks in back-to-back races.
Despite the mathematics, I feel more nervous for him after the Japan Grand Prix than before with Sebastian Vettel now also homing in, who until last Sunday was a dismissed outsider.
As a former British Formula 1 driver myself, I find myself hoping compatriot Button wins the title.
Ross [Brawn] will be definitely be more concerned by the lack of pace in Japan than the lack of silverware
But his Brawn team-mate Rubens Barrichello is a former team-mate of mine and a good friend, and if he's champion then it would be a great story.
I'm also immensely impressed with Vettel and he would be a very worthy champion, as he will surely be one day. But I'll be disappointed if Button loses it now.
As ever he was a lucky boy in Suzuka. Had Adrian Sutil and Heikki Kovalainen not got together in front of him, I think he would have been passed by the longer-fuelled Robert Kubica and ended up with no points. Nothing.
He also had a bit of luck with the safety car in Singapore - but you make your own luck to some extent and he continues to do that with stunning and critical overtakes, demonstrated once again by the move on Kubica at the chicane early in the race.
You have to assume that Button can take a fifth or two seventh places in Brazil and Abu Dhabi but he really needs a 'champion's drive' to satisfy the fans and media that he is a worthy title holder.
Mind you, David Coulthard and I agree that we would both have loved to 'limp home' to become world champion with six victories. Many others have won with more dominant cars and fewer victories.
I'm pleased Brawn didn't clinch the constructors' crown by dint of Williams' Nico Rosberg receiving a penalty two hours after the race.
They would have missed their platform on global TV and in the paddock to celebrate a spectacular performance.
Button analyses his Japan race
They can't really fail to win it now with half a point required, unless they receive some kind of points penalty for rule infringements. Let's not go there!
Their reliability has been extraordinary after such a late start with the car following the uncertainty of last winter. They haven't messed up pit-stops, their strategy has almost always been smart, and they have allowed the drivers to race each other.
I've known Ross for 19 years and I've worked with him in sports cars and F1. Despite the strong likelihood he will win both titles, it was clear after the Japanese Grand Prix that he was really disappointed - he expected Barrichello, from sixth on the grid, to get a podium.
And, generally, both drivers were struggling for pace. This will trigger alarms about the remaining two races and where they head with next year's car design.
Brawn, Button, and Barrichello are prepared to wait for the titles. The trophies don't come with a calendar attached to them - it doesn't matter how early you win them.
Ross will definitely be more concerned by the lack of pace than the lack of silverware.
Vettel's performance for Red Bull was outstanding all weekend.
In qualifying, he did one run per session, and while many buried their cars in the barriers he made no mistakes.
The lack of running, because of rain on Friday, meant eight drivers were new to an F1 car around Suzuka.
That made for a tightly packed and competitive field, and an unforgiving circuit saw enormous amounts of damage and an unprecedented three red flags in qualifying.
Not for Vettel, though. His qualifying lap for pole position was mesmerising with two wild moments in high-speed corners which he ultimately controlled with no time loss.
His start, the first two laps of the race and the first couple of laps after his pit-stops were in a class of their own.
Christian Horner said to me that Vettel was so fast after his stop they were worried they hadn't put any fuel in - which sums it up perfectly.
So a great job from Vettel but to be fair, Toyota's Jarno Trulli and Lewis Hamilton kept him honest and fully deserved their podiums.
It's going to be a thrilling end to the season.
Martin Brundle was talking to BBC Sport's Sarah Holt.