The Chase for the Sprint Cup Series Championship shifts to the Texas Motor Speedway in Fort Worth this weekend for Sunday's AAA Texas 500.  With seven races down and three to go in this year's Chase for the Sprint Cup, it's looking like it will be a two-man battle for the championship in NASCAR's premier series.  Tony Stewart's win coupled with a ninth-place finish for Carl Edwards last Sunday at Martinsville Speedway allowed Stewart to trim Edwards' points lead to just eight.  None of the 12 drivers in the Chase field have been mathematically eliminated from the championship yet.  Heading into Texas, 89 points separate Edwards from 12th-place Ryan Newman.  Jimmie Johnson is now 43 points behind Edwards, as his hopes of a record-extending sixth straight series championship are fading away.