The Sydney Opera House and Auckland's Sky Tower will be lit up simultaneously to highlight the joint bid from Australia and New Zealand in the final hours before FIFA decides on the venue for the 2023 Women's World Cup.
The lights will go on in advance of a decision from the 37-member FIFA Council on Thursday in Europe, expected about 2 a.m. local time Friday on Australia's east coast and 4 a.m. in New Zealand.
The co-confederation bid is favoured to win in a two-way contest with Colombia following the late withdrawal of a bid from Japan.
Football Federation Australia chief executive James Johnson on Wednesday said the southern bidders were cautiously optimistic.
"We need to remain focused on finishing the job," Johnson told the Australian Associated Press. "Our goal has been to convince the FIFA Council members who vote on the merits of our bid and we're continuing to work on this into the late hours."
Australia spent millions of dollars on its unsuccessful bid for the men's 2022 World Cup in a deflating result for local soccer fans and officials.
Johnson is confident the technical evaluations this time give the Australia-New Zealand a strong chance.
"It's a far more transparent process than what the processes were last time we were in this situation in 2010," Johnson told AAP. "Our focus has been on the merits and not the politics, that's the way we have been from day one."
The combined bid performed significantly stronger than Colombia in the FIFA inspection report — scoring 4.1 to 2.8.
None of the remaining bidders has ever hosted a senior men's or women's World Cup. Victory for the Australia and New Zealand would be the first time a World Cup has been split across two confederations.
Australia joined the Asian Football Confederation after qualifying for the 2006 World Cup, and New Zealand is part of the Oceania Football Confederation.
The tournament is due to be staged from July 10-Aug. 20, 2023 and will see the field expanded from 24 to 32 teams.