As Kasey Kahne took the chequered flag in Atlanta for his second win of the year the massed ranks of NASCAR began to figure out exactly what had to be done next Saturday night in Richmond in the final race before the top twelve drivers are locked into the title deciding Chase.

Kahne's win, taking the lead on the final restart from Kevin Harvick, moved the Dodge driver up five places in the overall rankings and out of immediate danger of falling out of a Chase place as the 190 points he banked moved him up to sixth.

However, Kahne is still one of eleven drivers whose Chase future is still, technically, undecided, and to understand how, and why you have to do battle with NASCAR's rather inelegant scoring system.

Under NASCAR's current scoring system the maximum points difference a driver can make up in a single race in 151. To do that he must win, which alone pays 185 points, and lead the most laps, which pays a further ten, while his rival finishes dead last without leading a lap.

Of course there are several caveats on that. Firstly, that assumes that both drivers are entered in Richmond, which barring a huge surprise you would expect anyone with chase chances to be. Secondly it does need a driver to finish dead last.

Those of you who have followed NASCAR this season will know the chances of a team that is actually trying finishing last are very low, with “start-and-park” teams filling the bottom three or four positions almost every week, completing only a handful of laps.

Taking that into account, and suggesting the highest a 'proper' team can finish is 40th gives you a maximum points difference of 142 points.

With one race remaining only three drivers who are currently out of the top twelve have even a mathematical chance.

All three are Toyota drivers, Brian Vickers of Team Red Bull, Kyle Busch (despite having four victories) and David Reutimann.

To say that Reutimann's chances are slim is being kind. He currently sits 132 points behind Matt Kenseth, the current first target for the three hopefuls, meaning that so long as Kenseth scores more than 53 points (37th place alone pays 52) Reutimann is outside the Chase regardless of how he fares.

Vickers' and Busch's chances, however, appear more favourable. Using the 142 point difference they can still overhaul everyone up to, and including, fifth place Carl Edwards, and Vickers sits only 20 points behind Kenseth, meaning that so long as Vickers tops the Ford driver by at least six places, anywhere in the field, the No.83 is in, the No.17 is out – although that doesn't take into account any bonus points the two score (see what I mean by inelegant).

Of course, while Kenseth is the first hurdle the Camry trio face for the Chase – and is the only hurdle within Reutimann's reach – there are still seven other drivers who they could replace, including Atlanta winner Kahne and Mark Martin (another driver with four wins this year).

All will be decided in the now traditional Saturday night decided at Richmond's 0.75 mile oval.

Have a calculator at the ready.