| ITF Women Solarino | 2018/03/07 10:35 | Anna Klasen v Romy Koelzer | 2-6,7-5,6-3 |
| DTB German Pro Series Women | 2020/06/18 12:30 | Carmen Schultheiss v Romy Koelzer | 6-7,6-7 |
| DTB German Pro Series Women | 2020/06/17 09:30 | Laura Siegemund v Romy Koelzer | 6-1,6-0 |
| DTB German Pro Series Women | 2020/06/16 14:10 | Laura Schaeder v Romy Koelzer | 2-6,5-7 |
| ITF W15 Heraklion | 2020/03/12 10:00 | Darya Astakhova v Romy Koelzer | 6-2,3-6,4-6 |
| ITF W15 Heraklion | 2020/03/11 08:30 | Sem Wensveen v Romy Koelzer | 3-6,6-2,2-6 |
| ITF W15 Heraklion | 2020/03/07 09:00 | Romy Koelzer v Rebeka Masarova | 3-6,0-6 |
| ITF W15 Heraklion | 2020/03/06 08:30 | Andreea Amalia Rosca v Romy Koelzer | 1-6,5-7 |
| ITF W15 Heraklion | 2020/03/05 08:30 | Martina Biagianti v Romy Koelzer | 6-7,1-6 |
| ITF W15 Heraklion | 2020/03/12 10:30 | Anna Klasen v Federica Arcidiacono | 7-6,1-6,7-5 |
| ITF W15 Heraklion | 2020/03/11 10:05 | Tamara Curovic v Anna Klasen | 5-7,0-6 |
| ITF W15 Heraklion | 2020/03/10 10:50 | Anna Klasen v Sem Wensveen | 2-6,6-1,10-5 |
| ITF W15 Heraklion | 2020/03/10 08:00 | Anna Klasen v Ema Bolebruchova | 6-1,6-3 |
| ITF W15 Heraklion | 2020/03/01 08:30 | Laura Svatikova v Anna Klasen | 7-5,6-3 |
| ITF W25 Altenkirchen | 2020/02/23 17:30 | Fabienne Gettwart v Anna Klasen | 5-7,6-4,10-8 |
| ITF W15 Stuttgart | 2020/01/21 13:15 | Julia Terziyska v Anna Klasen | 6-3,5-7,6-3 |
| ITF W15 Stuttgart | 2020/01/20 10:00 | Anna Klasen v Enola Chiesa | 6-0,6-2 |