Two Australian Open tournaments were held in 1977, one in January and another in December.
The unusual double edition resulted from a scheduling change. The January tournament ran from 3 to 9 January at Melbourne's Kooyong Lawn Tennis Club, while the second was staged from 19 to 31 December, also in Melbourne. Both were officially counted as 1977 Australian Opens.
Roscoe Tanner won the January men's singles title, defeating Guillermo Vilas in straight sets. Kerry Melville Reid captured the January women's title. In December, Vitas Gerulaitis won the men's championship and Evonne Goolagong Cawley won the women's title.
This is why historical records sometimes list two champions for 1977. The calendar shift was intended to move the event from its traditional late-December period toward an earlier position, but the transition created two tournaments in one calendar year. The next major scheduling gap came in 1986, when no Australian Open was played before the January 1987 edition.