Thomaz Koch Open era singles finals (3-2) Open era singles finals (3-2)

| Outcome | Date_ | Championship | Surface | Opponent_in_the_final | Score_in_the_final |
|---|---|---|---|---|---|
| Winner | 1969 | Caracas, Venezuela | Clay | Mark Cox | 8–6, 6–3, 2–6, 6–4 |
| Winner | 1969 | Washington, U.S. | Hard | Arthur Ashe | 7–5, 9–7, 4–6, 2–6, 6–4 |
| Winner | 1971 | Caracas, Venezuela | Clay | Manuel Orantes | 7–6, 6–1, 6–3 |
| Runner-up | 1976 | Khartoum, Sudan | Hard | Mike Estep | 4–6, 7–6, 4–6, 3–6 |
| Runner-up | 1976 | Nuremberg, Germany | Carpet | Frew McMillan | 6–2, 3–6, 4–6 |