Graeme Swann admitted that England were left shell-shocked by the manner and magnitude of their incredible three-wicket defeat at the hands of Kevin O'Brien on Wednesday night, but insisted that the team's best response would be to put the result right out of their minds as they turn their attention to Sunday's crucial showdown against the Group B pacesetters, South Africa, in Chennai.

As Ireland's celebrations continued long and loud in the wake of the biggest result of their lives, England flew out of Bangalore knowing that their World Cup campaign is in danger of sliding out of control, after three consecutive fixtures - including a thrilling tie with India - in which their frailties have been exposed with both bat and ball. However, with contests against South Africa, Bangladesh and West Indies still to come, qualification for the quarter-finals remains in their own hands, so long as they revert to winning ways at the earliest opportunity.

"If we are going to win this World Cup - which we truly believe we can - we've got to go out and prove it, and we do that first and foremost in the field," said Swann. "Four or five days ago, the whole world was saying 'Oh my God, England can win' this - because we didn't get destroyed by that invincible Indian team. We know the fickle nature of the world, and we're going to ignore that and just carry on and play the best cricket we can."

At 111 for 5, chasing a massive 328 for victory, Ireland's chances of victory were seemingly non-existent, until Kevin O'Brien climbed onto the offensive with the innings of his - or anyone else's - life. His incredible 50-ball century slammed England's bowlers onto the defensive, and in partnership with first Alex Cusack and then John Mooney, Ireland clawed their way back into the contest.

"It's disappointing to lose any game of cricket," said Swann. "But it was one where we got ourselves into a position of such dominance, to then have it taken away from us is quite shell-shocking. Every now and again someone wakes up and has the best day of their life - and yesterday Kevin O'Brien did that. We should have bowled better; we certainly could have bowled better, but that's tarnishing the knock he had - personally I think he won the game rather than we lost it."

Despite that assertion, the cracks in England's performance were visible long before O'Brien got going, with Matt Prior dropping a steepling chance behind the stumps to reprieve Ed Joyce, and Swann himself was visibly peeved with his fielders before claiming three quick wickets to put his team firmly in charge of the contest. "A lot of guys were peed off, and rightly so," he said. "We got ourselves into a position where the opposition were 110 for five, with 20 overs to go. That's a game an international team of the calibre that we feel we are should win 10 out of 10."

"It's annoying in the extreme, but I'm not taking anything away from Kevin O'Brien and the performance of his life," Swann added. "It's the best knock I've seen in a long time. If a guy gets 100 off 60 balls [sic], a guy gets 100 off 60 balls. There's not a lot you can do, except say we should have bowled differently - and in the next game we will do. If we start panicking and thinking we're the disgrace that half the people on Twitter thought we were last night, there's no point in us playing.

"You can always bowl better," he added. "When a guy hits that many sixes you are obviously putting the ball in the wrong place. We could have bowled more yorkers and more slower balls wide of the wicket - that's easy in retrospect to say. When you're in the middle and the pressure is on with a guy going great guns, it can be difficult to think clearly. But we back ourselves to be professional and think clearly, so in future that's certainly something we have to look at."