Top-ranked Ireland have put aside their stuttering 2019 form with a clinical 27-3 victory over main pool rivals Scotland to open their Rugby World Cup campaign convincingly in Yokohama.
Forwards James Ryan, Rory Best and Tadhg Furlong all scored tries in the first 25 minutes and winger Andrew Conway secured the bonus point with the fourth in the second half.
Scotland, with only a Greig Laidlaw penalty goal, tried to get their expansive running game going but were hamstrung by Ireland's defence and slippery conditions from persistent drizzle.
Injury-prone flyhalf Johnny Sexton had given up the kicking duties early, and there are concerns over head injuries to flanker Peter O'Mahony and centre Bundee Aki.
After an unsuccessful Six Nations defence, Ireland were desperate to start well in Japan.
The first two tries came from clean lineout ball, easing some worries over coach Joe Schmidt's team and his much-debated call to leave go-to jumper and caller Devin Toner at home.
The opening try on six minutes featured the rampaging second-row pair of Iain Henderson and Ryan. Henderson burst through the middle to set Ireland's dominant pack up close to Scotland's line before Ryan powered over.
Ireland's second was simpler, with hooker Best following up another accurate throw near the Scottish line to mark his 121st Test with a try.
Scotland tested the aerial skills of the relatively inexperienced back three of Conway, Jordan Larmour and Jacob Stockdale - forced on Schmidt by minor injuries to Keith Earls and Rob Kearney - and forced some errors.
It was all too easy for the Irish pack, who can be unstoppable if allowed to recycle possession. They obliged again as Furlong made it three tries from three forays into their opponents' 22-metre zone.
Long-threatened rain held off until late in the first half, only galvanising Ireland's stranglehold when the disappointing Scots tried to have a go early in the second term but were unable to get through well-organised defence.
Irish fans had one more try to cheer as Conway added the bonus point just before the hour.
By that stage, scrumhalf Conor Murray had assumed kicking duties and a not-noticeably injured Sexton left the park, testing Ireland's already depleted squad.
With Ireland expected to be too strong in six days for a Japanese eight, troubled up front by Russia in their opener, Schmidt can effectively start preparing for a likely quarter-final against South Africa.
Scotland, if they can advance, will almost certainly face New Zealand in the last eight.