In 1969 Sullivan relocated to Sydney and joined the
Gordon Rugby Club. He spent some time in reserve grade in that first season in Sydney first grade but in 1970 he regained his
state position in a match against Scotland and he represented for Sydney against those same visitors. An injury picked up in New Zealand prevented Davis from leading the side in the Test match in Fiji on the way home and Sullivan debuted as an Australian Test captain in the Wallabies' narrow 21–19 victory against Fiji. He had already captained the side in two mid-week games during the New Zealand leg. In 1973 Peter Sullivan retained the Test captaincy in the two Test series against
Tonga and was at the helm in the 2nd Test boil-over when Tonga got up 16–11. Howell writes of this period as "the lowest ever point of Australian rugby". He led the Wallabies on the
1973 Australia rugby union tour of Europe, and played in six of the nine matches including the Test loss against Wales. He was injured and did not take the field in the test against England, where the Wallabies were captained by
John Hipwell. All told Sullivan captained the Wallabies in four Tests through 1972–1973 and in nine tour matches. He played twenty-eight matches for Australia, thirteen of them Tests. Howell writes that he was "a vigorous, aggressive player who played to the maximum when wearing the green and gold". ==Rugby league career==