A good start is half the battle, and for Ireland it was a very good start indeed as the Scots were swept away in Yokohama on Sunday morning.
Still, the real battles are yet to come. Japan are up next in Pool A before games against Russia and Samoa so progression to the quarter-finals should not be an issue.
There, Joe Schmidt's men are now likely to face South Africa who were beaten by the All Blacks in a blockbuster Pool B opener.
For now though they get to savour a fine first-game performance.
The RTÉ panel of Donncha O'Callaghan, Fiona Coghlan and Bernard Jackman were all positive in the aftermath of today's success, with O'Callaghan adamant it lays down a huge marker.
"Executing the plan, that gets massive confidence," he said. "Maybe the criticism before was, there's no Plan B. Well there's no need for Plan B when your fundamentals are really strong. That's what we showed today. Players stepped up.
"We're in a really good position. If you were looking from any other camp now you'd be envious at what we have going on. "
Jackman agreed: "We couldn't have done more. This weekend has been really pleasing. The standard of South Africa v New Zealand was top class but the other top tea,ms haven't really impressed that much. We have put our hands as being contenders."
Coghlan meanwhile expects Japan to target a win against the Scots rather than the Irish.
"I think they should be (targeting Scotland)," she said.
"Depending on how Scotland respond to this, Japan could have a crack at them. Obviously they're going to look to perform in front of their home crowd and try to take a scalp, with Ireland the No 1 team and stuff like that. But I think their coach Jamie Joseph would be wise enough to say, 'let's focus on the Scotland game."