| Tournament | Round | Joan Ashton | Betty Billing |
| 23.08.1998 August (SA) | 4 | 320 | 299 |
| 12.09.1998 September (SA) | 3 | 375 | 327 |
| 25.10.1998 October (SA) | 5 | 325 | 357 |
| 16.01.1999 January (SA) | 5 | 335 | 266 |
| Head-to-head after 4 games | 3 | 1 | |
| Average score | 338.75 | 312.25 | |
| Spread: | 106 | -106 | |