| WTA Hong Kong Qual | 10/07 02:00 | 45 | [413] Guarachi Mathison, Alexa v Sawayanagi, Riko [236] | 6-4,6-3 | |
| Hua Hin, Singles W-WITF-THA-07A | 09/27 03:00 | 26 | [236] Sawayanagi, Riko v Yue Yuan [455] | 0-6,2-6 | |
| Hua Hin, Singles W-WITF-THA-07A | 09/25 06:10 | 25 | Sawayanagi, Riko v Punnin Kovapitukted | 6-4,6-2 | |
| WTA Guangzhou Qual | 09/17 06:00 | 46 | [154] Pattinama Kerkh., L. v Sawayanagi, Riko [237] | 6-1,7-5 | |
| WTA Guangzhou Qual | 09/16 04:45 | 45 | [488] Sun, Xu Liu v Sawayanagi, Riko [237] | 3-6,4-6 | |
| WTA Tokyo Qual | 09/09 06:30 | 45 | [173] Basak Eraydin v Sawayanagi, Riko [242] | 4-6,7-6,6-3 | |
| WTA Dalian | 09/06 05:10 | 25 | [242] Sawayanagi, Riko v Diatchenko, Vitalia [250] | 4-6,4-6 | |
| US Open Women Qual | 08/24 17:45 | 45 | Allie Kiick v Sawayanagi, Riko | 6-4,6-3 | |
| US Open Women Qual | 08/22 17:55 | 44 | [235] Sawayanagi, Riko v Muhammad, Asia [138] | 2-6,7-6,6-3 | |
| WTA Nanchang Qual | 07/22 08:00 | 45 | [225] Sawayanagi, Riko v Xiaodi You [434] | 6-3,2-6,1-6 | |
| ITF Women Tianjin | 07/20 02:00 | 26 | [313] Jing-Jing Lu v Sawayanagi, Riko [225] | 3-6,6-2,7-5 | |
| ITF Women Tianjin | 07/17 07:00 | 25 | Ren, Jia Qi v Sawayanagi, Riko | 0-6,1-6 | |
| ITF Women Naiman | 07/10 02:00 | 25 | [315] Jing-Jing Lu v Sawayanagi, Riko [221] | 6-2,5-7,6-4 | |
| Kofu, Singles W-WITF-JPN-02A | 06/15 01:00 | 26 | [476] Erina Hayashi v Sawayanagi, Riko [214] | 6-4,6-1 | |
| Kofu, Singles W-WITF-JPN-02A | 06/14 02:35 | 25 | Reina Takahashi v Sawayanagi, Riko | 4-6,4-6 | |
| French Open Women Qual | 05/23 11:05 | 44 | [144] Tereza Martincova v Sawayanagi, Riko [214] | 6-4,6-3 | |
| ITF Women Kurume | 05/19 02:10 | 27 | [426] Erina Hayashi v Sawayanagi, Riko [215] | 6-1,1-6,6-3 | |
| ITF Women Kurume | 05/18 02:25 | 26 | [351] Olivia Tjandramulia v Sawayanagi, Riko [215] | 6-4,0-6,3-6 | |
| ITF Women Kurume | 05/16 03:05 | 25 | Miyahara, Mihoki v Sawayanagi, Riko | 3-6,3-6 | |
| ITF Women Fukuoka | 05/11 01:00 | 26 | [293] Wongteanchai, Varatchaya v Sawayanagi, Riko [217] | 7-5,6-4 | |
| ITF Women Fukuoka | 05/10 03:55 | 25 | Yukina Saigo v Sawayanagi, Riko | 0-6,6-4,2-6 | |
| ITF Women Gifu | 05/03 01:00 | 25 | [200] Sawayanagi, Riko v Arina Rodionova [198] | 6-2,3-6,5-7 | |
| ITF Women Anning | 04/24 05:15 | 25 | [207] Sawayanagi, Riko v Valentini Grammatikopoulou [196] | Retired | |
| Zhengzhou, Chine | 04/19 06:20 | 26 | [40] Peng, Shuai v Sawayanagi, Riko [207] | 6-1,6-4 | |
| Zhengzhou, Chine | 04/18 05:55 | 25 | [208] Kato, Miyu v Sawayanagi, Riko [207] | 6-7,0-6 | |
| ITF Women Nanning | 04/11 05:30 | 25 | [203] Sawayanagi, Riko v Qianhui Tang [464] | 1-6,5-7 | |
| ITF Women Kashiwa | 04/05 02:15 | 25 | [405] Ninomiya, Makoto v Sawayanagi, Riko [200] | 5-7,6-3,6-3 | |
| Kofu, Singles W-WITF-JPN-02A | 03/31 01:00 | 27 | [194] Na-Lae Han v Sawayanagi, Riko [206] | 6-2,6-2 | |
| Kofu, Singles W-WITF-JPN-02A | 03/30 04:05 | 26 | Chihiro Muramatsu v Sawayanagi, Riko | 3-6,3-6 | |
| Kofu, Singles W-WITF-JPN-02A | 03/28 02:35 | 25 | Yoshitomi, Yumeko v Sawayanagi, Riko | 3-6,0-6 |