Stadium: Court 2 Round: 14 Ground: Hardcourt outdoor
| WTA Ostrava | 2021/09/18 13:00 | Katarzyna Piter v Bernarda Pera | 0-6,1-6 |
| WTA Hamburg | 2021/07/05 08:00 | Katarzyna Piter v Katharina Gerlach | 2-6,5-7 |
| WTA Bad Homburg | 2021/06/21 14:30 | Petra Kvitova v Katarzyna Piter | 4-6,6-1,6-4 |
| WTA Bad Homburg | 2021/06/20 09:00 | Katarzyna Piter v Nastasja Schunk | 7-6,2-6,7-6 |
| WTA Bogota | 2021/04/03 16:25 | Katarzyna Piter v Marina Melnikova | 5-7,0-6 |
| WTA Guadalajara | 2021/03/06 23:20 | Olga Govortsova v Katarzyna Piter | 6-0,6-2 |
| WTA Abu Dhabi | 2021/01/05 08:05 | Katarzyna Piter v Jessica Pieri | 4-6,0-6 |
| ITF W80 Tyler | 2020/10/26 19:20 | Mayo Hibi v Katarzyna Piter | 6-4,6-7,10-5 |
| WTA Tenerife | 2021/10/17 10:00 | Stefanie Voegele v Kirsten Flipkens | 6-3,7-6 |
| WTA Tenerife | 2021/10/16 09:30 | Cristiana Ferrando v Kirsten Flipkens | 6-4,5-7,3-6 |
| WTA Indian Wells | 2021/10/07 18:00 | Caroline Garcia v Kirsten Flipkens | 5-7,6-4,6-0 |
| WTA Indian Wells | 2021/10/05 21:25 | Kirsten Flipkens v Katarzyna Kawa | 2-6,6-2,6-3 |
| WTA Indian Wells | 2021/10/04 19:40 | Kirsten Flipkens v Theadora Rabman | 5-7,7-6,6-1 |
| WTA Chicago | 2021/09/27 17:20 | Kirsten Flipkens v Danielle Rose Collins | 4-6,2-6 |
| WTA Chicago | 2021/09/26 18:05 | Kirsten Flipkens v Rebecca Marino | 6-4,6-7,6-4 |
| WTA Miami | 2021/03/25 17:30 | Jelena Ostapenko v Kirsten Flipkens | 6-2,5-7,6-3 |