Who has the edge in the Chase, Jimmie Johnson or Brad Keselowski?

It's that time of year. Barring disaster for the top two drivers, the Chase for the NASCAR Sprint Cup is a two-man race. That's not to say that the sort of misfortune that quashed Denny Hamlin's title aspirations in Sunday's TUMS Fast Relief 500 at Martinsville can't happen to Jimmie Johnson and Brad Keselowski. A part can break at any time, as did a bolt to the master switch on Hamlin's No. 11 Toyota on Sunday. A stuck throttle can send a car hurtling into the outside wall, as was the case with Jeff Gordon in the first Chase race at Chicagoland. A sudden twitch by another driver can trigger a wreck that wipes out one of the leaders, as was the case when Sam Hornish Jr.'s car collided with Johnson's in the 2009 Chase race at Texas. In 2009, however, Johnson had a large enough margin to absorb a 38th-place finish. This year, his margin heading to Texas is razor-thin. In winning at Martinsville, Johnson turned a seven-point deficit entering the race int...