An estimated 15,000 to 20,000 interstate and international fans will also provide a significant bonanza for the local economy with a potential further direct spend of $10m more on hotel rooms, meals, transport, alcohol and retail expected.

The highly anticipated Wallabies and Ireland clash at Allianz Stadium is likely to challenge the record 44,063 fans who attended the Test against England at the venue two years ago, with more than a third of those expected to be supporting the Irish - many of whom have travelled from overseas.

ANZ Stadium is preparing for more than 80,000 the following day as NSW looks to wrap up the Origin series against Queensland. Roughly 10,000 of those are likely to be travelling supporters, most from north of the border, but they will be joined by fans from New Zealand, Papua New Guinea, the United States and Ireland.

Revenue of up to $15m is expected from the Origin match, with more than half of that to be spent on ticketing. The rest will be generated from food, drink and merchandise sales within the venue, with an average minimum spend of $40 per fan expected.

"It hasn’t just been Sydneysiders buying tickets and jerseys for these events. Pleasingly, fans from all over Australia and overseas have bought tickets to these games," NRL chief commercial officer Andrew Abdo said.

"We’re expecting a near capacity crowd out at ANZ Stadium on Sunday. It’s a win for fans, for the game and for Sydney."

A spokeswoman for Tourism Minister Adam Marshall said the government's agency Destination NSW had projected attendance figures for this year but declined to release them because they were being provided exclusively to News Corp.

An average ticket price of $87 should ensure the Wallabies Test garners some $4m in ticket revenue, plus extra for corporate hospitality.

Conservative estimates suggest 50,000 beers will be bought throughout the Test, although that figure is expected to be substantially higher and could rival the amount of amber ale purchased during day one of an SCG cricket Test.

Venue staff are also expecting to sell 5000 portions of hot chips, 3000 meat pies and 2000 burgers.

That should ensure the Wallabies Test generates revenue upwards of $7m.

Much more will be spent over the course of the weekend in Sydney, which also hosted the Women's State Of Origin on Friday night, and will stage two rugby league Pacific Tests at Campbelltown Stadium on Saturday, making it one of the biggest ever sporting weekends in the Harbour City.

Albert Stafford, a tourism economist at Stafford Strategy who works with the Sydney-based industry group, the Tourism and Transport Forum, said travelling sports fans could easily spend $500 a day on accommodation, food and drink, transport and retail therapy.

"If you've got the facilities and you've got the product then people will spend," Mr Stafford said.

"People get caught up in the euphoria. If your team wins you tend to go out on the town and enjoy and if your team loses you tend to drown your sorrows, so you're caught either way.

"As long as you're giving people great experiences, fabulous range of food and beverage options, public transport and private and you've got good retail and everything's open, visitors coming for major sporting events tend to spend well."