Diego Schwartzman defeated Kei Nishikori 6-4 6-2 in the Rome Masters quarter-final on clay. The upset overturned the form book — Kei Nishikori came in ranked #703, leading the head-to-head 3–1, defending last year's quarter-final. Diego Schwartzman narrowed the head-to-head to 3–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2021-02-02 | Atp Cup | RR | hard | Diego Schwartzman | 6-1 6-7(4) 6-0 |
| 2018-08-27 | US Open | R32 | hard | Kei Nishikori | 6-4 6-4 5-7 6-1 |
| 2017-05-08 | Madrid Masters | R32 | clay | Kei Nishikori | 1-6 6-0 6-4 |
| 2017-02-13 | Buenos Aires | R16 | clay | Kei Nishikori | 5-7 6-2 6-2 |
Averages from each player's recent completed matches (20 vs 20). ATP, WTA & Challenger.