| 24‑Jul‑2023 | Atlanta | Hard | QF | 439 | 9 | (1)Taylor Fritz [USA] d. (PR)Nishikori | 6-4 6-2 | | 0.44 | 1.7% | 1.7% | 65.5% | 68.4% | 45.0% | 1/4 | 1:13 |
| 24‑Jul‑2023 | Atlanta | Hard | R16 | 439 | 156 | (PR)Nishikori d. (Q)Juncheng Shang [CHN] | 6-4 7-6(3) | | 1.42 | 6.6% | 0.0% | 65.6% | 77.5% | 61.9% | 1/3 | 1:36 |
| 24‑Jul‑2023 | Atlanta | Hard | R32 | 439 | 63 | (PR)Nishikori d. Jordan Thompson [AUS] | 7-6(5) 7-6(5) | | 1.06 | 0.0% | 3.3% | 71.4% | 75.4% | 53.8% | 4/4 | 2:25 |
| 10‑Jul‑2023 | Chicago CH | Hard | QF | 501 | 250 | Alex Michelsen [USA] d. (WC)Nishikori | 7-6(13) 3-6 6-1 | | 0.88 | 3.7% | 2.8% | 63.6% | 67.6% | 46.2% | 3/7 | 2:36 |
| 10‑Jul‑2023 | Chicago CH | Hard | R16 | 501 | 302 | (WC)Nishikori d. (Alt)Skander Mansouri [TUN] | 7-6(1) 6-4 | | 1.88 | 1.6% | 3.2% | 65.1% | 85.4% | 68.2% | 1/1 | 1:42 |
| 10‑Jul‑2023 | Chicago CH | Hard | R32 | 501 | 215 | (WC)Nishikori d. (6)Alexis Galarneau [CAN] | 7-6(3) 6-1 | | 1.44 | 5.2% | 1.7% | 70.7% | 73.2% | 52.9% | 0/2 | 1:24 |
| 3‑Jul‑2023 | Bloomfield Hills CH | Hard | R16 | 501 | 180 | (3)Denis Kudla [USA] d. (WC)Nishikori | 6-4 3-6 6-3 | | 0.89 | 5.4% | 5.4% | 57.0% | 64.2% | 52.5% | 8/12 | 2:21 |
| 3‑Jul‑2023 | Bloomfield Hills CH | Hard | R32 | 501 | 237 | (WC)Nishikori d. Adam Walton [AUS] | 6-1 6-2 | | 2.03 | 5.9% | 3.9% | 58.8% | 73.3% | 71.4% | 4/4 | 1:06 |
| 12‑Jun‑2023 | Palmas Del Mar CH | Hard | F | | 1118 | (WC)Nishikori d. (Q)Michael Zheng [USA] | 6-2 7-5 | (ch) | 1.31 | 6.6% | 0.0% | 68.9% | 64.3% | 47.4% | 5/8 | 1:41 |
| 12‑Jun‑2023 | Palmas Del Mar CH | Hard | SF | | 423 | (WC)Nishikori d. (Q)Gustavo Heide [BRA] | 6-4 6-2 | | 1.31 | 1.8% | 1.8% | 64.3% | 77.8% | 55.0% | 1/1 | 1:26 |
| 12‑Jun‑2023 | Palmas Del Mar CH | Hard | QF | | 254 | (WC)Nishikori d. Adam Walton [AUS] | 6-4 6-2 | | 1.37 | 0.0% | 1.8% | 71.4% | 67.5% | 56.3% | 1/2 | 1:23 |
| 12‑Jun‑2023 | Palmas Del Mar CH | Hard | R16 | | 258 | (WC)Nishikori d. (7)Mitchell Krueger [USA] | 4-6 6-3 6-2 | | 1.38 | 2.7% | 0.0% | 73.3% | 67.3% | 65.0% | 0/3 | 2:19 |
| 12‑Jun‑2023 | Palmas Del Mar CH | Hard | R32 | | 333 | (WC)Nishikori d. Christian Langmo [USA] | 6-2 6-4 | | 1.55 | 0.0% | 4.1% | 67.3% | 72.7% | 62.5% | 2/3 | 1:43 |
