The giant wing scored his 39th Test try for his country – making him the top international try-scorer currently competing in the competition – as Warren Gatland’s men began their Japan tournament with a 43-14 victory over Georgia.
Wales scored six tries in total at the City of Toyota Stadium and have arrived in the Japanese capital ahead of facing the Wallabies this weekend.
North knows he and his team-mates will have to go up another level to come out on top.
“At a World Cup you have to focus on your next job,” he said.
“That first half against Georgia showed the intensity we wanted to go with. In the second half we lost our way a bit and maybe came off the gas. We should have turned it up a bit more.
“Fair play to Georgia, they obviously fronted up well in the second half. What should have been a more dominant performance saw us let them in the game again.”
Looking ahead to Australia, North added: “The form Australia are carrying into this means they have grown again as a team. They are playing some unbelievable rugby.
“We know we will have to be at our best. In the second half against Georgia we were nowhere near where we need to be to beat Australia. They are a tough beast.
“They have skills from one to 15, physicality, and speed. We will have to be on the money straight from the off and expect the unexpected.
“They have so many good players and trick plays – we have to be on our mettle.”
Meanwhile, tighthead Dillon Lewis, who made his Rugby World Cup bow against Georgia, says he can’t wait for a second crack at Australia in the Japanese capital of Tokyo on Sunday.
The Cardiff Blues tighthead prop appeared as a second-half replacement for Tomas Francis in Wales’ 43-14 win over Georgia and is now preparing for the round two clash with the Wallabies.
Lewis helped his country to a 9-6 victory in Cardiff in November 2018 which was the last time Wales met Australia. The 16-cap forward is hoping for a repeat performance and result this weekend.
“It’s something we can take into the game on the weekend – it’s massive to get those wins against the southern hemisphere teams,” said Lewis.
“Getting those wins under our belts during the autumn last year is something we can look back on.
“We can see what we did right in those games and it will be big as we go into this game on the weekend.
“We’ve seen Australia and their set-piece has improved a lot so that will be an area we will be looking at.
“From a defensive point of view we know what Australia can do with ball in hand and they are a dangerous and exciting team.
“If we get our defence right it should make for a really good game.”
