England 274 for 4 (Morgan 124*, Bopara 101*, Murtagh 3-33) beat Ireland 269 for 7 (Porterfield 112, Rankin 4-46) by six wickets
Scorecard and ball-by-ball details
In so many ways this was a fantastic day for Ireland cricket: close to 10,000 people at international cricket's newest venue, perfect weather, a hundred from their captain a new-ball spell that left England reeling. Yet it may also have felt like a bit of a kick in the teeth as Eoin Morgan, who grew up playing his cricket at Malahide, produced a scintillating career-best hundred to ensure the visitors chased down a testing total with a convincing seven overs to spare.
For both teams, the bowling was the weaker suit and Ireland's could not withstand the onslaught. Morgan, who was welcome to the crease by boos but applauded for his landmarks, and Ravi Bopara added 226 for in 28 overs, a record fifth-wicket stand in one-day internationals and England's joint second-best for all wickets, after they had been tottering on 48 for 4. Tim Murtagh bowled his 10 overs straight through to finish with 3 for 33 but Ireland's spinners were disappointing and their fill-in medium-pacers could not provide control.
Bopara ended the match with a stream of boundaries, reaching his maiden ODI hundred off 74 balls - the second fastest for England behind Kevin Pietersen's 69-ball effort against South Africa. He went four, six, four against George Dockrell to ensure he did not run out of runs before Morgan finished the match with another blow over the ropes.
For Morgan, who was also Man of the Match when these sides met two years, this was an especially timely innings. He has been short of runs for England in recent times - this was his first ODI hundred since September 2010 and his first half-century since last August - and, with his continued commitment to the IPL, needed to reaffirm his credentials as England's key middle-order player, especially ahead of captaining against Australia.
England certainly needed them here. William Porterfield's sixth ODI hundred had formed the cornerstone to Ireland's competitive 269 for 7, which became an even more imposing total when England's inexperienced top order was blown away by accurate seam bowling.
Michael Carberry completed a forgettable ODI debut when he was lbw to Trent Johnston for 10 having earlier dropped two catches in the outfield and bowled one over for 12. Murtagh then claimed two wickets in three balls, forcing Luke Wright to chop on and then ending Gary Ballance's debut innings second ball when the left-hander feathered an edge to Gary Wilson trying to leave the ball.
James Taylor mixed some punchy drives with less convincing prods and was bowled by Murtagh. England were 48 for 4, a full house basking under the warm sun were finding their voice and the Guinness was being lined up. Ashley Giles and the England selectors may also have been a little twitchy.
In the end, though, the victory came at a rollicking pace as Morgan and Bopara dispatched the ball to all parts. It bodes well for the future of the venue that its first ODI can produce a pitch where 270 is chased down.
Morgan brought out his full range of strokes - one early cover drive off Kevin O'Brien pinged to the boundary - and he soon dominated against the spin, which diluted a key part of Porterfield's attack. His hundred, the fifth of his ODI career and fourth for England, came from 94 balls and it was brought up with a scorching six over extra cover off Johnston.
Because of his backstory Morgan will make the headlines, but Bopara's role was another massive tick in his column during a season where he has appeared a cricketer revived after last year's problems. Using the experience he has built up, but has often threatened to waste, he was happy to fly under the radar while Morgan made the running, then as the target neared start to expand his strokeplay.
He had 36 off 43 when he struck two huge sixes off Paul Stirling and then made hay against the friendly medium pace of Kevin O'Brien and John Mooney. Having previously fallen for 96 in ODIs he made sure he finally secured three figures in emphatic fashion.
The importance of this match to Ireland was huge - with it being broadcast around the world and played in front of a record attendance - and the captain Porterfield took it upon his shoulders, with a measured 142-ball innings, to ensure England knew they had been in a hard-fought contest.
He reached his hundred in symbolic style, pulling his county colleague and former Ireland team-mate Boyd Rankin for six. Porterfield's previous five hundreds have come against Bangladesh and fellow Associate nations so this one, despite the shadow nature of England's team, arguably stands atop. That his team's bowling performance was a reality check does not dilute his innings.
There were subplots throughout, from county team-mates facing off against each other, two Irish captains (as in 2011) and an England debut for a former Ireland pace bowler who had 37 caps for them. Rankin made a nervous start but finished with a career-best 4 for 46 despite not completing his full 10 overs.
Rankin's first scalp for his new country - he became the eighth player to appear in ODIs for two nations - came when he squared up Stirling and his second wicket came in more unconventional fashion when Ed Joyce's back foot slid back, as he played to the off side, and rocked the base of leg stump, which dislodged a bail.
Only Rankin appeared to notice and pointed at the bail, leading to the umpires consulting the TV evidence, which soon showed that Joyce was out. The dismissal also provided a curious double: at the 2007 World Cup, Joyce and Rankin were on opposite sides and Rankin removed the left-hander with his first ball in the group match.
Ireland's progress, though, remained solid. Porterfield was given a couple of early deliveries to clip off his hip and later picked up boundaries through the off side. England's side felt a specialist pace bowler short and Tredwell was introduced in the 15th over. He should have provided England with a breakthrough when Niall O'Brien, on 14, top-edged a sweep but Carberry made a mess of the chance running in from deep midwicket as the ball bounced out of his hands. England's fielding was below its best throughout.
Tredwell soon took the fielders out of the equation by making another one grip to beat the left-hander on the back foot and hit the top of middle stump then trapped Wilson lbw. Kevin O'Brien joined Porterfield in a stand that had set the platform for a Powerplay boost only for O'Brien to pick out midwicket when he pulled a short delivery from Bopara. The innings stagnated during the fielding restrictions, five overs bringing just 16 runs, before Morgan's gamble with Carberry injected some life back into proceedings.
The sixth-wicket stand with Mooney was worth 63 when Porterfield was bowled off his pads - from way outside leg stump - by Rankin who then added Mooney. Ireland beaten by Ireland, you could say.
Andrew McGlashan is an assistant editor at ESPNcricinfo