ATLANTA — John Isner rode an overpowering service game to his fourth Atlanta Open title, beating fellow American Ryan Harrison 7-6 (6), 7-6 (7) on Sunday before a friendly crowd at Atlantic Station.

Isner has won two straight ATP tournaments since bowing out of Wimbledon in the second round, and will move up two spots in the world ranking to No. 18.

Isner has claimed one-third of his 12 ATP titles in Atlanta, where he's reached the final in seven of the tournament's eight years and was champion for three straight years from 2013-15. He had 23 aces to the fourth-seeded Harrison's 10.

The 32-year-old Isner won the Hall of Fame Open last week in Newport, Rhode Island.

The match followed service in the first set to force a tiebreaker.

Harrison rallied from a 2-4 deficit to level the breaker at 6-6 only to see Isner win with a sizzling forehand to the deep right corner.

Isner went 75 straight service games and seven-plus matches without being broken before Harrison passed him on the forehand side early in the second set. That ball, at 40-30 Harrison, was originally called out but, after Harrison challenged, a replay revealed that it just caught the line.

Isner broke back in the next game when Harrison sent what looked like an easy forehand long.

From there, the friendly foes remained on serve to bring another tiebreaker upon Isner's 18th ace.

Trailing 6-7, he fired consecutive aces, and then took the title.