Ireland powered past Six Nations rivals Scotland 27-3 to put themselves in the box seat to reach the quarter-finals at the Rugby World Cup on Sunday.
Three push-over tries in the first half did the damage before wing Andrew Conway grabbed a fourth after the break to secure a bonus-point win, with games to come against Japan, Russia and Samoa in Pool A.
With a sea of green-clad Ireland supporters dominating the stands at a packed but wet International Stadium Yokohama, Ireland were in no mood to be nice to their Six Nations rivals.
In a brutally physical game, in which the medics were rushed off their feet, Ireland bossed the breakdown and held a commanding 19-3 lead at half time.
As the intensity of the rain increased in the second half it was Ireland who relished the deteriorating weather most with a further eight points.
"I think we started really well. We were positive. We wanted to attack" said Ireland captain Rory Best.
Obviously with the conditions in the second half, it became more of an arm wrestle but we know how good a team they are and we're delighted with the win.
"That was a good start for us but we know ... how much we need to improve going forwards."
Conor Murray was given a dream ride behind a rampant forward pack, directing traffic with aplomb, particularly with an on-target kicking game, and pre-match concerns about Ireland's reshuffled backline quickly evaporated.
Scotland, meanwhile, did not help themselves with a weak defensive effort while being unable to penetrate the green wall in front of them.
The bonus-point win put Ireland level with hosts Japan with their first-round victories in Pool A, and the two go head-to-head next weekend.
James Ryan, Best, Tadhg Furlong and Conway scored for Ireland with Johnny Sexton and Murray landing a conversion each and Jack Carty kicked a penalty.
For Scotland, Greig Laidlaw's first-half penalty was their only score.
There was concern in the Scotland camp about Hamish Watson who was stretchered off just before half time with a knee injury.
The outstanding flanker had made 14 tackles up to that point in the face of a constant wave of green attacks.
Bundee Aki and Josh van der Flier required blood-bin treatment with Aki failing a head knock assessment.
Peter O'Mahony also required a head injury assessment and Murray took over Ireland's kicking duties when Sexton was being treated for a knock.
Scotland attacked hard at the start but once Ireland weathered the initial onslaught, Iain Henderson thundered upfield to set up fellow lock Ryan for the opening try.
Best scored the second for Ireland from a lineout drive and Scotland found themselves 12 points down before a Laidlaw penalty put them on the board.
But it was short-lived joy for Scotland as when they returned to Ireland territory from the restart, a wayward pass went to ground and was fly-kicked more than half the length of the field, where Stuart Hogg was caught in possession over the line.
From the resulting scrum, CJ Stander stormed forward to pave the way for Furlong to touch down and Ireland had their third try from their third foray into Scotland's 22.
Scotland were then 16 points in arrears, and the highest deficit ever overturned in a World Cup match is 15 by Romania against Canada in 2015.
The Scots tried to claw their way back in the opening exchanges of the second half, no doubt inspired by their 31-point recovery to draw with England earlier this year.
But a 15-minute period of control went unrewarded and when Ireland regrouped, Conway scored the bonus-point fourth try and Carty sealed the game with a penalty.
"We didn't start with the energy, accuracy and aggression needed to beat Ireland," Scotland coach Gregor Townsend told a news conference. "When you give them a 15-20 point start, it is hard to come back."