For the first time in Australian professional men's football, a top-tier match will begin with a large-scale show of support for the LGBTIQ community, as Sydney FC open their Big Blue blockbuster with a large-scale rainbow flag display.

In a match looming as the club's most important regular-season game in several years, the players of Sydney FC and Melbourne Victory will walk out at Allianz Stadium behind a large rainbow flag in celebration of the Sydney Gay and Lesbian Mardi Gras parade, and in support of the LGBTIQ community.

United: Josh Brillante, Flying Bats president Emily Shrubb, Graham Arnold, Sydney Rangers FC president Joseph Roppolo and Alex Brosque. Credit:Wolter Peeters

Players from the world's biggest lesbian football club, the Flying Bats Women's FC, and Australia's first football club for gay men, Sydney Rangers FC, will carry the flag in front of an expected crowd of 20,000 on Friday night, as part of a short on-field ceremony to help tackle discrimination in sport.

Sydney Rangers president Joseph Roppolo praised the initiative led by Sydney FC, and was hopeful of convincing Football Federation Australia to introduce a "rainbow round" in future seasons, coinciding with the Mardi Gras on the first weekend of March.