Dubai: Afghanistan's seemingly inexorable rise in the cricket world took another step in the right direction here on Tuesday as they defeated favourites and joint-defending champions Ireland in their opening world Twenty20 qualifiers.

The Afghans - who came within one place of reaching the 2011 World Cup finals - beat the Irish in a thrilling Group A contest by 13 runs.

They were not alone in upsetting the odds as wildcard entrants the United States defeated Scotland by six wickets also in Group A while Kenya were stunned by hosts United Arab Emirates, who had only been invited as they are the hosts, losing by 15 runs in Group B.

The Netherlands - joint holders with Ireland from the 2008 tournament - defeated Canada by six wickets in the other Group B clash in a series that will see two teams progress to the finals in the West Indies which runs from April 30 to May 6 with Pakistan as defending champions.

After Tuesday's results, all the four beaten sides find themselves in must-win situations while they are also aware of the fact that even if they win their matches on Wednesday, Thursday will be judgement day for them when Ireland goes head to head with Scotland in the late afternoon match in Dubai and Kenya takes on the Netherlands in the early afternoon match in Abu Dhabi.

Afghanistan made Ireland pay a heavy price for its sloppy fielding and uncharacteristic batting.

Ireland dropped no less than half a dozen catches in the field, then slipped from 52-1 to 78-5 in its 140-run chase and finally failed to finish off the game when it required 16 runs off the last 11 balls with three wickets standing.

For Afghanistan, it was its third recent victory over Ireland after it had earlier beaten undoubtedly the best Associate side in the 50-over format ICC World Cup Qualifier 2009 in South Africa by 22 runs, then it won a four-day first-class ICC Intercontinental Cup match by seven wickets in Dambulla last month before winning in the shortest version of the game on Tuesday.

Afghanistan's hero was Mohammad Nabi, who first struck three fours and two sixes in a rapid 25-ball 43 not out that lifted his side to 139-8, and then picked up 2-25 to help Afghanistan dismiss Ireland for 126 with four balls to spare.

Afghanistan coach Kabir Khan was delighted with his side's performance.

"It is very heartening to beat a top side like Ireland on a consistent basis. This reflects that we are learning and learning fast," said the 35-year-old former Pakistani test and one day fast bowler.

"It is certainly a jump start for my side as Ireland is the best side in the tournament. The victory has given us a tremendous boost and confidence.

William Porterfield, whose dismissal by off-spinner Karim Sadiq was crucial as he had made 35 off 23 balls, was disappointed with the loss.

"It is disappointing if you can't chase seven runs an over and are bowled out in 20 overs," he said.

"There is no doubt that we didn't play well but let's not forget that Afghanistan also played well.

"The equation for us is pretty simple and straight now. We need to win the remaining two matches to progress to the Super Four stage and get our ambitions back on track."