Sri Lanka 303 for 7 (Chandimal 100*, Mendis 51) beat Ireland 216 (Porterfield 73, O'Brien 64, Shanaka 5-43) by 76 runs (D/L method)
Scorecard and ball-by-ball details
Dasun Shanaka has the batting build of an unobtrusive nurdler, and his bowling seems of the innocuous wicket-to-wicket variety. He is a cricketer who invites underestimation.
In his embryonic international career, his impact has been with bat or ball, never both. But on his ODI debut against Ireland at Malahide, he married both disciplines to bring victory to Sri Lanka in spectacular style.
There are decent debuts, and then there is this. Shanaka's day begun by harrumphing 42 off 19 balls, and ended with him becoming only the 12th bowler in ODI history to take five wickets on debut. All enough for Sri Lanka to take victory, by virtue of a D/L recalculation after rain, by 76 runs.
All year, he has revelled in embarrassing those who have put him down. In January, 16 of the 46 deliveries the Saracens Sports Club bowled to him in a domestic T20 were pummelled for six.
In February, he was used as a relief bowler in a T20I against India and responded with 3 for 16.
In May, he was a slightly incongruous name in Sri Lanka's touring party, until 112 against Leicestershire pushed him into the Test team. Once there, he promptly bundled out three of England's top four within eight balls.
Just as in the First Test at Headingley, Shanaka was brought on more in hope than expectation, with Angelo Matthews needing to end an irritating opening stand.
There had been concerns that Sri Lanka's packed batting - Upul Tharanga returned at No. 8 - would leave too much of an onus on Shanaka's bowling. But under muggy Malahide skies, Shanaka promptly got a delivery to swing in appreciably to uproot Paul Stirling's off stump, and soon after tempted Ed Joyce into an aberrant swipe to Dinesh Chandimal behind the stumps.
These dismissals, Ireland's two most prized wickets, gave Sri Lanka a grip on the game, and Shanaka would return to ensure they did not relinquish it.
The upshot was that Ireland will have to wait to end their six-year run without defeating a Full Member in a home ODI, a statistic unbecoming for a cricket nation of such aspiration.
For spells of Ireland's innings Sri Lanka's hold on the game was threatened, as Kevin O'Brien forged worthy alliances with William Porterfield and Stuart Poynter, and an especially fruitful one with Sri Lanka's fielders.
There are two sorts of roulette players: those who cash in when they have struck lucky and those who double down, convinced one moment of fortune will beget another and they can bankrupt the casino by the time the night is out. One imagines that O'Brien is the sort who would either return from Monte Carlo with a new yacht or having lost his house trying.
Having reached five, O'Brien advanced down the pitch to Seekkuge Prasanna's legspin, and attempted to chip the ball to secure a couple. He was too early on the delivery, mistimed his shot and proceeded only to hit the ball straight to Kusal Perera at long on. But Perera misjudged the ball, just as O'Brien had, fumbled a routine catch and ended up taking it while his feet were over the rope.
Some would have regarded this as a cue to rein themselves in but to O'Brien this was only an excuse to double down. After facing three more balls, O'Brien pulled Nuwan Pradeep to fine leg, into Dhananjaya de Silva's hands but then through them: another six. Another five later, and O'Brien heaved Pradeep to long off where Angelo Matthews, running over his shoulder, saw the ball fall to the ground once more.
Soon after followed a rain-enforced break, but it did quell O'Brien's flirtation with peril, especially with the asking rate at nine: he thumped a ball straight to short fine leg, but was reprieved once more. So the four deliveries that could have ended O'Brien's innings instead produced 20 runs.
Given that fielders were never going to dismiss him, Sri Lanka instead relied on the umpire to award O'Brien lbw playing across Pradeep. The upshot was that Sri Lanka's reputation as merciless against Associates was maintained.
As for Chandimal, it has been five years since his last ODI century, and the roar when he ended that run spoke of awareness that such a wait did scant justice to his talent.
This was an innings of style, in Chandimal's pristine drives and flicks to the legside, but above all defined by impeccable placement and savvy. Chandimal did not recourse to power hitting, and nor did he need to: in making 100 not out from 107 balls, he scored only six fours but ten twos and 50 singles.
To see this innings it was possible to imagine that the revolution in ODI batting had never happened, but Chandimal correctly deduced that any score over 250 would be onerous to chase.
Either side of an 88-run partnership with Matthews, Chandimal forged two substantial stands with debutants. First Kusal Mendis, doughty as a novice number three in the Test series in England, scored a half-century that exhibited finesse and some resplendent straight driving. Then Shanaka emerged, in no mood to play with such subtlety, and plundered 24 in five deliveries from Max Sorensen.
For Ireland, the day brought joy to a debutant of their own. Barry McCarthy was handed his Ireland cap by John Mooney, the cricketer who has been anointed to replace.
There are obvious parallels. Both are Leinster-reared from strong cricketing families: Mooney's elder brother and McCarthy's younger sister are internationals. Both are zestful cricketers who bowl around 80mph, provide ballast to the lower order - not that McCarthy showed it here, slashing his fifth ball behind - and are fine fielders.
It was apt that McCarthy's debut was at Malahide. A testing spell to Ben Stokes in the net three years ago earned him a recommendation to Durham, and then a professional contract. Last summer, he became the first Irishman since the 19th Century to play county cricket before making his international debut.
So many felt his selection for Ireland overdue. McCarthy took only two balls to vindicate them, eliciting Danushka Gunathilaka to edge to slip. "It's a beautiful day," belted out the tannoy system.
McCarthy would doubtless have been of a mind to agree, but not those in the crowd, who had to enlist their umbrellas, which should be compulsory for any Irish cricket fans, for protection from the intermittent showers.
A combination of the weather and the football - Ireland are unfortunate that both these ODIs coincide with European Championship matches for the two Ireland sides, and the Malahide club house was packed to witness Northern Ireland's victory - contributed to an underwhelming crowd, only narrowly into four figures.
As McCarthy and Ireland's other 80mph seamers, O'Brien's canny cutters apart, were lined up by Sri Lanka, Ireland had cause to be grateful for their returnee: Boyd Rankin, playing his first ODI for Ireland for four years.
He had only played one international at Malahide before, when he took 4 for 46 for England against Ireland in 2013. Here, his extra pace yorked Shanaka and helped limit Sri Lanka to just 25 from the last four overs. But Shanka would return to extend Ireland's anxious wait for a marquee home win, and with bowling of archetypal Emerald Isle ilk.