To be eligible to compete in the Chase for the NASCAR Sprint Cup, drivers must start each race for which they have qualified, unless the sanctioning body finds reason to waive that requirement. That change, announced in a bulletin on Wednesday morning modifies the language of Rule 22.214.171.124.a, which last year required drivers to attempt to qualify for each event to retain Chase eligibility. Under the current provision, drivers still must attempt to qualify for each race, but they also must start every race for which they qualify successfully, unless NASCAR authorizes otherwise. A driver does not lose Chase eligibility for attempting to qualify for a race and failing to make the field. The clarified rule would apply in a situation where Kurt Busch, for example, were to qualify for the Coca-Cola 600 at Charlotte, race in the Indianapolis 500 on Sunday (as he did last year), but fail to return to Charlotte in time to start the Cup race. In that event, NASCAR would be unlikely to grant a waiver. On the other hand, NASCAR already has indicated that Brian Vickers, who will miss the first two events of the season while recovering from offseason heart surgery, retains his Chase eligibility because of a medical exception.