Primarily a second-rower, he played for the Balmain Tigers, Eastern Suburbs Roosters, North Queensland Cowboys and Paris Saint-Germain.
A Dubbo junior, Sing represented the New South Wales under-19 side in 1987, before being signed by the Balmain Tigers.
[2][3] In Round 19 of the 1988 NSWRL season, Sing made his first grade debut in Balmain's 16–22 loss to the Western Suburbs Magpies.
In 1995, he joined the newly established North Queensland Cowboys, playing in their inaugural game against the Sydney Bulldogs.
[6] Sing's father, Noel, was also a professional rugby league player, playing for the Penrith Panthers between 1971 and 1973.