She was ranked in the top ten female players during the mid-1960s, and in 1966 she won the French Open Mixed Doubles title[1] with Frew McMillan, defeating Ann Haydon-Jones and Clark Graebner in three sets.

[2] In April 1965 Van Zyl reached the final of the British Hard Court Championships at Bournemouth but was beaten in straight sets by Ann Haydon-Jones.

[3] She reached the semifinal of the French Open singles in 1967, beating Billie Jean King in the quarterfinals and then losing to Lesley Turner Bowrey.

[5] Van Zyl reached the finals of the South African Championships singles event on three occasions, winning the title in 1963 and 1975 and ending as runner–up in 1965.

From 1964 to 1976, she played in 11 ties for the South African Federation Cup team and compiled a 12–7 win-loss record.