Stadium: M Round: 45 Ground: Hardcourt outdoor
| ITF Women Nantes | 2017/10/31 12:05 | Lottner, Antonia v Osaka, Mari | 2-6,2-6 |
| ITF Women Montreux | 2018/09/07 13:00 | Zimmermann, Kimberley v Osaka, Mari | 7-5,6-4 |
| ITF Women Montreux | 2018/09/06 08:00 | Osaka, Mari v Martina Trevisan | 6-3,6-2 |
| ITF Women Montreux | 2018/09/04 09:30 | Osaka, Mari v Kilnarova, Monika | 6-2,6-1 |
| ITF Women Budapest | 2018/08/25 12:40 | Osaka, Mari v Marfutina, Maria | 1-6,2-6 |
| ITF Women Braunschweig | 2018/08/22 09:00 | Zarycka, Anastatsia v Osaka, Mari | 6-4,7-5 |
| ITF Women Porto | 2018/07/24 09:30 | Sabino, Lisa v Osaka, Mari | 6-2,6-1 |
| WTA Bucharest Qual | 2018/07/14 11:15 | Claire Liu v Osaka, Mari | 6-0,3-6,6-4 |
| ITF Women Denain | 2018/07/06 09:00 | Bolsova Zadoinov, Aliona v Osaka, Mari | 6-1,6-4 |
| Hiroshima, Japon | 2018/09/09 05:20 | Lottner, Antonia v Zhang, Yuxuan | 3-6,4-6 |
| US Open Women | 2018/08/23 15:00 | Di Lorenzo, Francesca v Lottner, Antonia | 6-4,7-5 |
| US Open Women | 2018/08/21 18:05 | Lottner, Antonia v Viktoriya Tomova | 6-1,6-1 |
| ITF Women Hechingen | 2018/08/09 15:30 | Tamara Korpatsch v Lottner, Antonia | 6-4,6-0 |
| ITF Women Hechingen | 2018/08/08 11:00 | Tereza Martincova v Lottner, Antonia | 4-6,0-6 |
| ITF Women Bad Saulgau | 2018/08/02 09:00 | Lottner, Antonia v Cadantu, Alexandra | 6-1,2-6,4-6 |
| ITF Women Bad Saulgau | 2018/08/01 10:30 | Lottner, Antonia v Kolodziejova, Miriam | 7-6,6-3 |
| ITF Women Bad Saulgau | 2018/07/31 15:30 | Lottner, Antonia v Kolodziejova, Miriam | 7-6,5-3 |