The bubble: How easy is it to pop and burst through?

If past performance is any indication, there's a better than 50-50 chance that either Brian Vickers or Kyle Busch will find themselves in the Chase for the Sprint Cup after Saturday night's race at Richmond, but the odds are against both of them making it in.

And it would take an unusual circumstance, the likes of which has happened only twice in this decade, for someone other than Matt Kenseth to find themselves on the outside looking in.

Looking at the Richmond results for a nine-year period beginning in 2000, on five occasions a driver outside of the top 12 would have leapfrogged his way into a Chase position, had the current format been in place. In fact, between 2003 -- the year before the Chase format was implemented -- and 2006, the driver in 12th position was either knocked out or, in the case of Jeff Gordon, tied for the final spot.

Of course, it's purely conjecture in some respects, because teams were racing under the conventions of the day and not using contemporary strategies to make the Chase field, especially before the field was expanded from 10 to 12 in 2007. But it's possible to extrapolate with a fair amount of certainty how the 12 spots would have been determined.

The past two seasons have been the most stable for drivers hoping to lock themselves into the top 12. In 2007, Kevin Harvick had a nearly insurmountable 128-point lead over Dale Earnhardt Jr. Last season, David Ragan and Kasey Kahne were both within 50 points of Clint Bowyer, but Ragan finished 32nd at Richmond and Kahne 19th.

But had there been a 12-man Chase format in place starting in 2003, things might have turned out very different under the lights at the Richmond Fairgrounds. If there's a scenario that Juan Montoya, Ryan Newman, Mark Martin and Greg Biffle would like to avoid Saturday night, it would be repeats of 2003 and 2006.

Six years ago, Robby Gordon had a 70-point cushion over Jeff Burton for 12th place heading into Richmond. But Gordon crashed twice and finished 29th, while Burton recorded a fourth-place finish, a swing of 89 points. In 2006, Biffle trailed teammate Carl Edwards by 64 points after 25 races, for what currently would be the final Chase spot. Biffle wound up sixth at Richmond and Edwards, who suffered damage in an early race accident with Jimmie Johnson, was saddled with a 35th-place finish, allowing Biffle to make up the deficit and then some.

Last chance

Win-to-get-in is still the ultimate goal for bubble drivers Kyle Busch and Brian Vickers.

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However, those are the exceptions rather than the rule. In the other three instances, the deficit has been much smaller. In 2005, Ryan Newman trailed Jamie McMurray by one point before bumping his way into the 10-man Chase. But had the field been expanded that year, Elliott Sadler -- who was 22 points behind Jeff Gordon for 12th -- would have gotten in (along with McMurray and Gordon, who tied with 2,972 points).

The first season of the Chase format, in 2004, was punctuated by Jeremy Mayfield's stirring victory at Richmond and that -- coupled with a logjam of eight drivers that approximates this season's standings -- allowed him to jump from 14th to ninth in the final "regular season" weekend. But he was only 19 points behind 12th place Bobby Labonte, who wound up being the odd-man out in the 12-driver format.

In 2001, Jeff Burton trailed Mark Martin by one point for what would have been the final Chase transfer spot heading into Richmond. He finished ninth and Martin wound up 19th, which would have resulted in them trading positions for the final 10-race Chase.

Burton is a special case. Beginning in 2001, the Virginia native found himself in 13th place heading into Richmond in three consecutive seasons. As earlier mentioned, he would have bumped his way into the Chase field in 2001 and 2003. In 2002, he was 70 points behind Kurt Busch but finished 39th.

However, even in seasons in which the standings have been sufficiently tight to allow for wholesale changes, the majority of the drivers clinging to spots inside the top 12 have stayed there. Of the 18 drivers "on the bubble" since 2000 -- within 100 points of 13th place with one race remaining -- 14 have gone on to make a 12-driver Chase format.

Even though Mayfield bumped his way in in 2004, Dale Jarrett and Kevin Harvick, both within 56 points of 12th, could not overcome the deficit in one race. In 2005, Kenseth, McMurray, Newman and Gordon were all within 62 points of the cutoff line -- and all four would have made the Chase, despite Sadler's heroics.

And it's certainly possible but highly unlikely for both Vickers and Busch to bump their way into the Chase field Saturday night. No two drivers have raced their way into the Chase field in the same season this decade. Harvick has come the closest on two occasions. In 2005, he finished 10th in the race and 14th in the standings, 35 points behind Gordon and McMurray. The previous season, he finished 12th in the race and 14th in the standings, 29 points behind Kahne.