NASCAR Preview: Go time in final race of Challenger round

DOVER, DE - "Now or never," "survive and advance," "all or nothing," whatever you want to call it, it's crunch time this weekend for the majority of the NASCAR Chase for the Sprint Cup drivers.<br /> <br /> The NASCAR Sprint Cup Series heads to Dover International Speedway on Sunday for the AAA 400, the final race of the Challenger Round. Following the event, the four winless championship-qualifying drivers lowest in points will be eliminated from title contention. The remaining 12 drivers will advance to The Contender Round and their points will be reset to 3,000.<br /> <br /> The points couldn't be tighter, and only one thing is assured