Rain threatens to derail the Twenty20 World Cup when big guns enter the fray this weekend, with Australia's opener against New Zealand and an India versus Pakistan blockbuster both at risk of being washed out, reports BSS.

Parts of Australia are facing a third straight La Nina weather event with a wetter-than-average summer expected, and downpours are forecast for Sydney and Melbourne from Friday through to next week.

But the Bureau of Meteorology is forecasting a "very high (90 per cent) chance of showers" and potentially thunderstorms, with no reserve days for group games. They only come into play for the semi-finals and final.

It looks equally gloomy for Sunday in Melbourne where India will face Pakistan in a hotly-anticipated clash with about 100,000 audience in the cavernous MCG and tens of millions more tuning in to watch the match.

A minimum of five overs a side is required to constitute a match.

The weather could also cause havoc in Hobart where games are scheduled for Friday and Sunday, although England's opener against Afghanistan in Perth on Saturday has a fine weather forecast.

Australia have a golden opportunity to become the first back-to-back T20 world champions, enjoying the advantage of being the only winners of cricket's shortest format to have a crack at defending the title at home.

But they begin their campaign on the back of a 2-0 series loss to England this month and with Finch admitting they were "tired" after a gruelling build-up.

Despite the tough lead-in, pace spearhead Pat Cummins insisted they were better placed after defying the odds to win last year's title.

Bd-pratidin English/Tanvir Raihan