Depending on the semifinal outcomes, Cardiff is ready to invite New Zealanders from around Britain to join the party at the stadium.
Richard Thomas, managing director of the city's marketing company Cardiff & Co, said: "At the last count there were around 60,000 New Zealanders in Britain - half of them in London, less than two hours from Cardiff.
"The rugby party in Cardiff, along with the final itself in Auckland, promises to create a truly global occasion. And if Australia were to tip out New Zealand, the pool of fans would be even bigger, with more than 100,000 Aussies living in Britain.
"The stadium is ready for the party. All we need is for the results [tonight] to fall the right way and we could see the biggest trans-global rugby festival ever.
"Cardiff is ready with a friendly welcome ... In Welsh we have a special phrase for it - croeso cynnes iawn i Gaerdydd - a very warm welcome to Cardiff. Rugby fans always get on well together and 10 or 20,000 Kiwis mingling with a 50,000-strong Welsh contingent would produce a fantastic atmosphere 12,000 miles away across the globe.
"All it takes now is a Welsh win."