COLOMBO - India and Australia hope to avoid adding to the list of great limited-overs upsets when they open their World Twenty20 campaigns against Afghanistan and Ireland on Wednesday.

In a potentially sensational double-header at Colombo's Premadasa stadium, George Bailey's Australia take on Ireland in Group B, ahead of India's Group A clash with Afghanistan. While many fans will assume victory is a formality, both Australia and India know better than to predict the outcome of a Twenty20 game.

"I will only rest easy when that game has passed," admitted Australian coach Mickey Arthur. "That's not through fear of failure. Ireland have been a giant-killer down the line. Any team in this competition can win if they have a good day."

The gritty Irish proved their worth when they stunned England at last year's 50-over World Cup in India, after knocking Pakistan out of the 2007 tournament in the Caribbean. Australia were handed a huge shock at the first World Twenty20 in 2007, when they were beaten by minnows Zimbabwe. Bangladesh knocked the West Indies out of the same tournament and the Netherlands beat hosts England at the 2009 edition. Ireland will be boosted by insights from former Australian fast bowler Craig McDermott, who left his home side earlier this year to join the Irish as their bowling coach. "Craig has fit in pretty well, working with the bowlers," said Ireland captain William Porterfield. "He has got a lot of confidence that we can go out there and beat anyone."

Porterfield added it was important to make a strong start in the competition. "In a group of three teams, you've got to win at least one game, if not two, to go through." The 12 teams have been divided into four groups for the preliminary league, with the top two from each advancing to the Super Eights round. Wednesday's second game may appear a mismatch, but Indian captain Mahendra Singh Dhoni said facing free-swinging Afghanistan, now in their second World Twenty20, was no easy task. "Wins don't come easy in international cricket and we are certainly not going to take any side lightly," said Dhoni, who led India to the inaugural World Twenty20 title in South Africa in 2007.

"We have to play our best cricket to beat Afghanistan. They are a good team and have improved a lot over the years." Afghanistan captain Nawroz Mangal said his side had come a long way since their World Twenty20 debut in the Caribbean in 2010, when they lost to India by seven wickets. "We are ready for the challenge," Mangal said. "Teams like Ireland have shown that the best can be beaten and we are inspired by that. We too want to beat a big team." Mangal said it was important to live up to the expectations of fans back home in the war-ravaged nation. "They expect a lot from us now," he said. "Earlier our fans just wanted us to match the big sides, now they want us to beat them." Both India and Australia go into the tournament chastened by defeats in warm-up matches in Colombo on Monday.