"We were outplayed," said Ponting as world champions Australia crashed to a 10-run defeat at the hands of the West Indies at the Brabourne stadium here on Wednesday night.
"There was a game here to be won and we were not good enough. We have to blame ourselves for some ill-disciplined batting and some ill-disciplined bowling."
The West Indies' stunning victory, on the back of a hat-trick from fast bowler Jerome Taylor, followed equally unexpected results on the previous two days that threw the eight-nation tournament wide open.
On Tuesday, a severely depleted Pakistan overcame the absence, on doping charges, of pace spearheads Shoaib Akhtar and Mohammad Asif to end Sri Lanka's 10-match winning streak with a four-wicket win in Jaipur.
A day earlier, world number two South Africa had been hammered by 87 runs by Stephen Fleming's New Zealand despite the Black Caps missing their frontline paceman Shane Bond due to a back injury.
The first round shockers mean both Australia and South Africa will not be guaranteed semi-final berths even if they win their two remaining league matches.
Hosts India, who beat England on Sunday, and the West Indies lead group A ahead of Australia. New Zealand and Pakistan are on top of group B, ahead of South Africa and Sri Lanka.
The second round of league matches starts on Friday when New Zealand take on Sri Lanka at the Brabourne stadium here.
Mahela Jayawardene's Sri Lankans need a win to stay in contention. The Kiwis will almost certainly book a semi-final berth with their second win.
"This is just the start the tournament needed," said former Australian captain Ian Chappell. "There is little to choose between the eight teams.
"Anyone can win this one. There are more twists and turns to come."
The unpredictable nature of one-day cricket was evident on Monday night when Australia, chasing West Indies' 234-6 under lights, lost five wickets for 37 runs to be restricted to 224-9 in their 50 overs.
Taylor, a 22-year-old Jamaican, became the first West Indian to take a hat-trick in limited-overs cricket to fashion a sensational win for the defending champions.
The right-arm fast bowler clean bowled Michael Hussey and trapped Brett Lee leg-before with the last two balls of his ninth over, the 48th of the innings.
Taylor then returned for the final over with Australia needing an improbable 16 runs and shattered Brad Hogg's stumps with his first delivery to complete a split hat-trick.
Australia next play old foes England in Jaipur on Saturday, a game Ponting said was "very important" in the context of the tournament.
"It is the first time Australia and England are meeting since the last Ashes battle," he said. "With a lot riding on the game as far as this tournament is concerned, I'm sure it will be another good game of cricket, hopefully one that we come out on top in."
The West Indians have eight days before their next game, against India, in Ahmedabad on October 26.
"We understand that India play pretty well at home," said West Indian vice-captain Ramnaresh Sarwan. "But we will go into that game with the same positive attitude and hopefully win that one as well."
Sarwan said that captain Brian Lara, who suffered a back spasm while batting on Wednesday, would be fit for the next match.
The West Indies have won five of their past six one-dayers against Rahul Dravid's home team.