Pat first came to the tennis world’s attention as a junior player in the early 1980s. He was ranked the top junior player in the world in 1981, and in 1982 he won the junior titles at both Wimbledon and the US Open. He turned professional in 1982 and won his first top-level singles title that year in Melbourne.
Pat established a reputation on the tour as a hard-fighting serve-and-volleyer and for wearing his trademark black-and-white checked headband and his cross earring.
In 1983, Cash became the youngest player to play in a Davis Cup final. He won the decisive singles rubber against Joakim Nyström as Australia defeated Sweden 3–2 to claim the cup.