England 199 for 6 (Foakes 61*, Curran 47*, Little 4-45) beat Ireland 198 (Stirling 33, Plunkett 4-35, Curran 3-45) by four wickets
Ireland went into their 10th ODI against England having won only once, at the 2011 World Cup, but when 19-year-old Little, one of six debutants in the match, claimed three of his four wickets to put England in trouble at 66 for 5 chasing 199 for victory, they could be forgiven for dreaming of another historic upset.
It took an unbroken 98-run partnership from Ben Foakes, also winning his first ODI cap, and Surrey team-mate Tom Curran to carry England over the line for an ultimately comfortable but unconvincing four-wicket victory.
Archer celebrated his highly anticipated first appearance in an England shirt with a wicket and a superb catch. But it was Liam Plunkett and Curran - arguably among Archer's biggest rivals for a final World Cup berth - who starred as England bowled Ireland out for 198 with 11 balls remaining in the innings, reduced to 45 overs per side because of a soggy outfield which delayed the start by two hours.
The target would normally be seen as easily achievable for the No.1 one-day side in the world who bat deep and love to chase. But what should have been an agenda-setting start to their World Cup run-in ended in some nervy moments for the tournament favourites, not least when Foakes survived an lbw appeal when on 37 which Ireland chose not to review and replays suggested could have been overturned.
Bearing in mind that England had rested a number of first-choice players in a match which came at the end of a week dominated by the axing of Alex Hales for recreational drug use. But it was some of the side's experienced campaigners who struggled.
The pursuit did not start well, with debutant Dawid Malan calling for treatment after appearing to injure his groin taking a quick single. He batted on in clear discomfort, his ability to run obviously impaired, and saw fellow opener James Vince dismissed to what would have been a beautiful pull from the bowling of Little had George Dockrell not taken a screamer diving to his left at midwicket.
Joe Root and Eoin Morgan followed cheaply, the latter to a brilliant Little bouncer which the England captain gloved to wicketkeeper Gary Wilson, before Little also had Malan caught behind for 24, at that point only the second visiting batsman to reach double figures. Joe Denly, playing his first ODI since 2009, followed soon after when Kevin O'Brien took another smart catch at midwicket.
David Willey and Foakes threatened steady England until Little returned to the attack with immediate effect as Willey sent a catch straight to fine leg, with England still shaky at 101 for 6.
Foakes then combined with Curran. Having been dropped by Lorcan Tucker off Mark Adair with England still needing 12, Curran then hit the winning runs with a boundary off a Little no-ball in a disappointing end to an otherwise memorable day for the bowler.
Little, a former hockey player who had made 10 T20I appearances but was playing his first ODI, ended with figures of 4 for 45 off eight overs.
England won the toss and put Ireland in. Archer's wicket was a gem, ending a decent knock by Adair - another on debut, who scored 32 off 30 balls in attempting to lift his side - with a 90mph yorker that uprooted off stump. Earlier, Archer had taken a superb diving catch to hand Curran England's first wicket of the innings, dismissing a dangerous-looking Paul Stirling.
Interestingly, Archer opened the bowling in tandem with Willey, who had previously appeared to question whether picking the Barbados-born talent could destabilise England's World Cup squad.
Archer has not been named in England's preliminary World Cup squad but has a chance to press his claims for a late inclusion. His first ball in international cricket was drilled to the boundary by Stirling amid a respectable opening spell.
William Porterfield survived an lbw appeal off Willey on the second ball of the innings, and at the end of the first Powerplay, Ireland were in good shape. They had reached 55 without loss when Curran struck in his second over, with the help of Archer, to dismiss Stirling.
Plunkett claimed the wickets of Porterfield and Tucker and, by the time Curran had O'Brien well caught by a diving Denly at backward point, Ireland's promising start had fizzled to 77 for 4.
An excellent piece of wicketkeeping by Foakes accounted for Andrew Balbirnie. As Balbirnie shied at a Denly wide, the batsman kept his back foot planted for what seemed like an age but, when he finally lifted his toe, Foakes - who had done well to collect the ball as it sailed a long way down the leg side - was waiting and lifted the bails for a sharp stumping.
Archer returned for a second spell that took care of Adair in eye-catching style, before Plunkett and Curran rounded up the innings. Unlike Archer, those two were named in England's preliminary World Cup squad but neither has been regarded as a shoo-in. Their latest performances will do their causes no harm ahead of the squad being finalised on May 23.