On Wednesday night in Bangalore, an Irish legend was born. For 123 glorious minutes Kevin O'Brien burned more brightly than the floodlights that illuminated the stadium, as an increasingly impassioned crowd cheered each thundering crack off his bat with ever greater fervour. Ireland were floundering at a rudderless 106 for 4 in the 23rd over when he entered the fray, they were at the brink of the most famous victory in their cricketing history when he departed 211 runs later. The crowd rose as one to cheer him off and tearful pride was writ large on the faces of his parents, who had watched every ball from the stands.

"I'm still speechless to be honest," O'Brien said after his breathtaking innings. "There's two proud people up there in the stands, and there's probably 4 million proud people back home. It's a fantastic day, not just for Irish cricket but for any Irish sport. Any time Ireland beat England, it's massive. All I can say is that it's a tremendous day and we're all very proud. It's going to be a good night and we'll celebrate as long and as loudly as we can.

"That's a long way the best innings I've ever played," he added. "It even eclipses playing in the back garden with Niall, where hitting out of the garden was out. I think anyone is going to struggle to beat that innings to be honest, and I'll take a few fines for that. I'll say that all night, a hundred off fifty balls in a World Cup in front of a billion people under lights against England, it doesn't get any better."

It was fitting that O'Brien became Ireland's leading run-scorer in one-day cricket in the course of his innings. His record-breaking century - the fastest in World Cup history - sealed the biggest chase the tournament has ever seen, smashing a record that had stood for 19 years, and helped Ireland soar to their first ever win over England. William Porterfield, Ireland's captain and the man O'Brien eclipsed on that run-scoring list, was effusive in his praise for what he called "an unbelievable knock".

"There's not many games where a team will be 111 for 5 with 24 overs gone and chase 320-odd and knock them off with a few balls to spare," said Porterfield. "It's an unbelievable knock, it's the best knock I've seen. It's got to rank as one of the best, if not the best, World Cup knock."

Porterfield was equally enthused about the team's victory and its place in Irish cricketing history, adding: "I think it's the biggest win that Irish cricket's ever had. Obviously there's the win against Pakistan [in 2007] that put us through the group but in terms of a one-off win it's the biggest we've ever had, and one of the best. It's the biggest chase in World Cup history and it's the biggest chase we've had in a long time. It's the best win in Irish cricket's history for me."

While Ireland had managed to just about keep afloat after the disaster of losing Porterfield to the first ball of the innings, their pursuit of 328 had been drifting into mediocrity before O'Brien strode to the crease. He reached the boundary three times within the first 10 deliveries he faced, displaying remarkable self-belief, and never looked back.

"I Just went out and tried to be positive," he said. "Just back my own ability and if the ball's there to hit, try and hit it, and hit it as hard as I can. It was obviously a tricky situation, it didn't help losing the fifth wicket for 111. We were backs-against-the-wall but we took a chance and we got the ball rolling and from there I don't think England had any answers for us. They didn't really know what they were up to with their bowling plans and we took advantage of that."

Porterfield suggested the turning point came when the Batting Powerplay was taken after the 31st over. The 32nd, bowled by Michael Yardy, was the most expensive of the innings until that point, but there was even more carnage to come. Three overs later O'Brien crashed James Anderson into the night sky and high over the midwicket boundary with scarcely believable force to smash another record, for the biggest six of the tournament, with a 102-metre behemoth. Five overs of fielding restrictions yielded 62 runs and with 99 needed at seven-an-over, for the first time the finish line became visible for Ireland.

"It was the turning point," said Porterfield. "We've obviously got plans and strategies before the game, but it's up to the lads in the middle to make that call [on taking the Powerplay]. They know how they feel out there and what they feel they can do, so I think it was a pretty good decision to take it then."

It was soon after that O'Brien truly began to believe that he could do more than simply bruise English egos, and that victory was actually achievable. "For me, it was probably at about 12 overs to go. We needed 80 or 90 off 12, about seven an over and the wicket out there was extremely flat, the ball was coming onto the bat nicely and it's a pretty small ground with a quick outfield. You pierce the ball through the infield and it's either two or four, and it helped that I was hitting the ball pretty cleanly as well."

There was a final twist to the tale, however, and when O'Brien was run out in the 49th over with 11 still needed one might have expected there to be some fluttering hearts in the Ireland camp. But O'Brien insisted that, even then, they felt victory was theirs for the taking.

"I knew John-boy [John Mooney] was there and he was hitting the ball extremely cleanly, and then Trent [Johnston] to come in. Trent's no tailender, he hits a big ball and he's a fantastic player coming in at No. 8 or 9 for us. I just knew if we didn't panic it was down to a run a ball, and they weren't really hitting their straps. They weren't hitting their yorkers and they were always giving us a four-ball - one an over - so we knew if we just sat on it, kept out the good ball and hit the bad ball that we'd walk to victory."

The win, with five balls to spare, was indeed ultimately a stroll, but Ireland's reaction was anything but. The Ireland changing room had bristled with increasingly nervous, fidgety energy until the explosion of emotion that came with Mooney's swat to the midwicket boundary, the players spilling onto the field in joyful delirium.

Ireland's cricketers, with an assortment of shaved, blond, blue and purple heads, brought colour and excitement to match England's epic against India at the same venue last week. O'Brien stood out more than most with his garish pink and blond mop, and his match-winning century will stand out in similar technicolor in the memories of all who saw it on a legendary night in Bangalore.

Liam Brickhill is an assistant editor at ESPNcricinfo