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