He turned professional in 1970. His first professional match was in March 1971, against Alex Higgins in the first qualifying round of the 1972 World Snooker Championship, resulting in a 4–11 loss. Gross had not played competitively for several years before the match, and admitted that he was out of practice and "played very poorly." Gross' next three professional competitions all ended with defeats in his first match. In the 1973 World Snooker Championship, Gross lost 2–9 to Perrie Mans, and at the 1973 Norwich Union Open he was eliminated 2–4 by Barron. At the 1974 World Snooker Championship he lost in the against David Taylor, 8–9. An 8–5 win over Maurice Parkin at the 1976 World Snooker Championship was followed by a 4–8 loss to Jim Meadowcroft in the next round.