3‑Mar‑1974 | Miami WCT | Hard | SF | 3 | 23 | Cliff Drysdale [RSA] d. (2)Okker | 6-0 1-6 7-5 | | | | | | | | | |
3‑Mar‑1974 | Miami WCT | Hard | QF | 3 | 85 | (2)Okker d. Mike Estep [USA] | 7-6(3) 6-7 7-6(1) | | | | | | | | | |
3‑Mar‑1974 | Miami WCT | Hard | R16 | 3 | 113 | (2)Okker d. Jim Mcmanus [USA] | 6-2 6-1 | | | | | | | | | |
3‑Mar‑1974 | Miami WCT | Hard | R32 | 3 | 39 | (2)Okker d. Han Jurgen Pohmann [GER] | 6-3 3-6 6-3 | | | | | | | | | |
5‑Mar‑1972 | Miami WCT | Hard | R32 | | | Ismail El Shafei [EGY] d. (3)Okker | 1-6 6-2 6-1 | | | | | | | | | |
4‑Apr‑1971 | Miami WCT | Hard | QF | | | (4)Rod Laver [AUS] d. (5)Okker | 6-3 6-0 | | | | | | | | | |
4‑Apr‑1971 | Miami WCT | Hard | R16 | | | (5)Okker d. Andres Gimeno [ESP] | 6-7 6-4 6-4 | | | | | | | | | |
4‑Apr‑1971 | Miami WCT | Hard | R32 | | | (5)Okker d. Phil Dent [AUS] | 6-2 6-4 | | | | | | | | | |