SCOTLAND 27 IRELAND 22
Scotland full-back Stuart Hogg stamped his name onto the Lions 15 jersey with two stunning tries that left Ireland's RBS 6 Nations campaign in dire straits.
Hogg lacerated Ireland's defence as Scotland triumphed 27-22 at Murrayfield, to make good on all their pre-tournament hype.
The Scots had proudly declared the 2017 vintage ready to blossom into their best Test team in a generation, and here Vern Cotter's side started that process in fine style.
Paddy Jackson's converted try saw Ireland rally from 21-5 down to lead 22-21, only for Greig Laidlaw to slot two late penalties and secure a fine victory.
Ireland appeared a shadow of the side that toppled back-to-back world champions New Zealand 40-29 in Chicago in November, with Joe Schmidt's men desperately craving a cutting edge.
Many Six Nations predictions had neutrals breezily dreaming of a Grand Slam decider when Ireland host England in Dublin on March 18.
Scotland spoiled Ireland's St Patrick's Day weekend party planning in spectacular fashion though, blowing the competition wide open in the process.
Scotland made a mockery of any Ireland pretensions to this year's title in a first-half dismantling of boss Schmidt's much-vaunted game plan.
Defence coach Andy Farrell must have been tearing his hair out in the stands as Ireland's rearguard action fell far too short of expected standards.
The visitors battered Scotland at the scrum, only to waste three fine try-scoring platforms from botched penalty lineouts.
Scotland were clinical in the extreme in contrast, peerless full-back Hogg ghosting home for the opener after Garry Ringrose stepped out of the line poorly in misreading Finn Russell's pass.
Any claims from Ringrose that he could have pulled off an intercept must have fallen on deaf ears, because the Leinster centre simply dropped a defensive clanger to gift Scotland their first score.
Scotland and Hogg then doubled their try tally at the close of the first quarter, with Ireland again guilty of lax defending.
A worrying misalignment between Rob Kearney and Keith Earls let Hogg stroll home again, while Munster wing Earls was left in no man's land as the Scots cemented their dominance.
Ireland appeared bereft of ideas, but somehow conjured a try for Earls after Tommy Seymour failed to intercept Simon Zebo's floated scoring pass.
Scotland struck again however, pulling off an ingenious lineout ruse for centre Alex Dunbar's try.
Ireland totally failed to notice the Glasgow midfielder lurking in the middle of a five-metre lineout, and Ross Ford's short throw created the all-too easy score.
Cotter's men turned around with a commanding 21-8 lead then, but Ireland hit back with Iain Henderson's score straight after the break.
Conor Murray burrowed close after a series of tight drives, before Ulster lock Henderson finished off Ireland's obdurate move.
Ireland botched a fine scoring chance when Murray blocked Russell's grubber to race clear. Murray fed Jamie Heaslip but the Leinster loose forward was unable to find Robbie Henshaw, with Sean Maitland intercepting to extinguish the danger.
Ireland went close again as Rob Kearney bumped off Huw Jones only to be dragged into touch at the last by Maitland.
Ireland totally bossed the third quarter and finally claimed their third score when Jackson forced a clean break to dot down at full extension.
Dunbar and Huw Jones could only watch on as the Ulster pivot scythed through, then posting the conversion to wrestle Ireland a one-point advantage.
Jackson was pinged for refusing to roll away at ruck however, allowing Laidlaw to slot the penalty and push Scotland back into a 24-22 lead.
Scotland had seven minutes to keep the ball to rebuff Ireland's second-half fightback, a job which was boosted considerably by Tommy Bowe's high tackle on Dunbar.
Laidlaw coolly posted the penalty - then banged over another to seal the deal.