Undated, Jul 31 (REUTERS) Big-serving second seed John Isner defeated Ryan Harrison 7-6(6) 7-6(7) in an all-American final to claim his fourth Atlanta Open title. For Isner, who saved set point in both sets, the win marks his second consecutive title yesterday since suffering a second-round loss at Wimbledon. The booming serve of Isner, who last week won the Hall of Fame Open in Newport, Rhode Island, proved to be the difference as the 32-year-old American won 85 percent of his first-serve points against his fourth-seeded opponent. By capturing his 12th title, Isner will move up two spots to 18th in the ATP rankings today and surpass Jack Sock as the top-ranked American player. Isner has now reached the Atlanta final in seven of the tournament's eight years. REUTERS SDR 0708