| 24‑Mar‑1970 | Johannesburg | Hard | R64 | | | Frank Mcdonald [RSA] d. Forbes | 6-2 6-3 3-6 3-6 6-0 | | | | | | | | | |
| 23‑Jun‑1969 | Wimbledon | Grass | R128 | | | Onny Parun [NZL] d. Forbes | 6-4 8-6 6-3 | | | | | | | | | |
| 16‑Jun‑1969 | London / Queen's Club | Grass | R128 | | | Patrice Beust [FRA] d. Forbes | W/O | | | | | | | | | |
| 4‑Apr‑1969 | Johannesburg | Hard | R64 | | | Dick Crealy [AUS] d. Forbes | 7-5 5-7 4-6 6-4 6-1 | | | | | | | | | |
| 4‑Apr‑1969 | Johannesburg | Hard | R128 | | | Forbes d. Allan Mcdonald [AUS] | 7-5 6-3 6-3 | | | | | | | | | |