The A-League's 2021/22 season will not kick off until Nov. 19, with organisers postponing the start of Australia's top flight soccer competition in the hope Covid-19 restrictions will ease across the country.

The league had planned for a 30 October start but Australia's two largest cities, Sydney and Melbourne, remain locked down as authorities grapple with a third wave of Covid-19 infections.

The first part of the season will be based on a conference system with five New South Wales state-based clubs and New Zealand's Wellington Phoenix playing each other in the opening six rounds.

The remaining Melbourne-based clubs as well as Adelaide United, Perth Glory and Brisbane will battle in the other conference, with most games played in southern Victoria state, Australian Professional Leagues (APL) said on Thursday.

APL said subsequent fixtures would be confirmed later, with the expectation that Covid-19 restrictions, including caps on crowds and travel curbs, will ease by the end of the year.

"The dates we chose to start the seasons were driven by vaccination progress," said APL Leagues Commissioner Greg O'Rourke.

"By the time we kick off, most of the states should have 80% double vaccination rates or be very close, which on the basis of the national plan should see crowds start to return, borders become navigable and quarantine requirements mitigated."

The postponement means the league will run through to 28 May, 2022, with the champions decided in the usual 'Grand Final' match at the end of the playoffs.

A-League champions Melbourne City open the season at home against Brisbane Roar on 19 November.

Australia's professional women's competition, the W-League, was also postponed to a 3 December kick-off, APL said.