John Isner defeated Ryan Harrison 7-6 7-6 in the Madrid Masters round of 32 on clay. The result followed the form book — John Isner came in leading the head-to-head 7–3. John Isner extended the head-to-head to 8–3.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2018-07-23 | Atlanta | F | hard | John Isner | 5-7 6-3 6-4 |
| 2018-02-26 | Acapulco | R32 | hard | Ryan Harrison | 6-3 7-6(5) |
| 2017-07-24 | Atlanta | F | hard | John Isner | 7-6(6) 7-6(7) |
| 2016-07-25 | Canada Masters | R32 | hard | Ryan Harrison | 7-6(3) 6-7(4) 6-4 |
| 2013-07-08 | Newport | R32 | grass | John Isner | 7-6(0) 6-2 |
| 2013-05-27 | Roland Garros | R64 | clay | John Isner | 5-7 6-7(7) 6-3 6-1 8-6 |
| 2013-04-08 | Houston | R32 | clay | John Isner | 7-6(4) 6-4 |
| 2013-01-07 | Sydney | R16 | hard | Ryan Harrison | 6-4 6-4 |
| 2012-07-09 | Newport | SF | grass | John Isner | 7-6(4) 6-3 |
| 2010-02-15 | Memphis | R32 | hard | John Isner | 6-1 7-5 |
Averages from each player's recent completed matches (20 vs 20). ATP, WTA & Challenger.