Stadium: Center Court Round: 19 Ground: Clay
| Wiesbaden, Simples W-ITF-GER-03A | 2019/05/01 12:10 | Gerlach, Katharina v Zaja, Anna | 4-6,6-3,0-6 |
| ITF Women Shrewsbury | 2018/11/06 14:15 | Gerlach, Katharina v Zaja, Anna | 4-6,4-6 |
| WTA Nurnberg Qual | 2018/05/19 13:05 | Gerlach, Katharina v Zaja, Anna | 6-7,3-6 |
| WTA Hamburg | 2021/07/05 08:00 | Magdalena Frech v Zaja, Anna | 0-0 |
| WTA Hamburg | 2021/07/05 08:00 | Jasmin Jebawy v Zaja, Anna | 2-6,3-6 |
| WTA Bad Homburg | 2021/06/21 11:30 | Zaja, Anna v Ann Li | 0-6,4-6 |
| WTA Bad Homburg | 2021/06/20 09:00 | Zaja, Anna v Julia Middendorf | 6-2,7-5 |
| ITF W25 Jonkoping | 2021/06/16 11:10 | Carol Zhao v Zaja, Anna | 6-4,4-6,6-2 |
| ITF W25 Jonkoping | 2021/06/15 08:10 | Zuger, Joanne v Zaja, Anna | 5-7,4-6 |
| ITF W25 Liepaja | 2021/05/29 08:00 | Zaja, Anna v Daniela Vismane | 6-1,3-6,4-6 |
| ITF W25 Liepaja | 2021/05/28 14:00 | Zaja, Anna v Kamilla Bartone | 6-0,6-2 |
| WTA Hamburg | 2021/07/05 08:00 | Piter, Katarzyna v Gerlach, Katharina | 2-6,5-7 |
| Wimbledon Women | 2021/06/22 18:05 | Gerlach, Katharina v Astra Sharma | 4-6,0-6 |
| ITF W60 Stare Splavy | 2021/06/17 07:55 | Gerlach, Katharina v Irene Burillo Escorihuela | 1-6,6-3,1-6 |
| ITF W25 Otocec | 2021/06/04 09:25 | Iva Primorac v Gerlach, Katharina | 6-4,6-4 |
| ITF W25 Otocec | 2021/06/03 09:55 | Raluca Georgiana Serban v Gerlach, Katharina | 2-6,3-6 |
| ITF W25 Otocec | 2021/06/02 13:35 | Marie Benoit v Gerlach, Katharina | 2-6,0-6 |
| ITF W60 Saint-Gaudens | 2021/05/12 07:00 | Anna Bondar v Gerlach, Katharina | 6-3,6-3 |
| ITF W60 Saint-Gaudens | 2021/05/11 13:00 | Gerlach, Katharina v Koval, Vlada | 6-1,6-4 |