By Reid Spencer, NASCAR Wire Service DOVER, Del.—Jimmie Johnson's run toward a possible sixth NASCAR Sprint Cup Series championship shifted into high gear Sunday at Dover International Speedway. On two fresh tires to polesitter Dale Earnhardt Jr.'s four, Johnson held off his Hendrick Motorsports teammate during a 26-lap green-flag run to the finish of the AAA 400 and made a significant dent in the series lead of Matt Kenseth, who finished seventh. Johnson picked up his fifth victory of the season, his record eighth at the Monster Mile—breaking a tie with Richard Petty and Bobby Allison—and the 65th of his career. The driver…

By Reid Spencer, NASCAR Wire Service   LOUDON, N.H.—Was this real or instant replay? For the second straight week, in the second race of the Chase for the NASCAR Sprint Cup, Matt Kenseth led Joe Gibbs Racing teammate Kyle Busch to the finish line — and for Kenseth, who has struggled at New Hampshire Motor Speedway, that added a dreamlike quality to the victory. The top seed in the Chase, Kenseth won Sunday's Sylvania 300 by .533 seconds over Busch as JGR asserted its superiority for the second consecutive week. A half hour after the race ended, the magnitude of the victory was…