Fans get into the swing of things before kick off.

Pat McCabe of the Wallabies is tackled by Sean O'Brien of Ireland.

Australia Wallabies' Adam Ashley-Cooper off loads the ball as he is tackled by Ireland's Jonathan Sexton.

The Rugby World Cup was turned upside down last night when Ireland scored a sensational 15-6 win over Australia at Eden Park.

The Wallabies had been in great form leading into this game, having won the Tri-Nations and put on a stunning display of running rugby against Italy a week ago.

But they were humbled by Ireland last night and it's a result that will have major ramifications for the remainder of the tournament.

1 of 7 JASON OXENHAM/Fairfax Media Irish fans celebrate their win over Australia. 2 of 7 JASON OXENHAM/Fairfax Media Irish fans celebrate their win over Australia. 3 of 7 JASON OXENHAM/Fairfax Media Irish fans celebrate their win over Australia. 4 of 7 GRAHAME COX/Sunday News Irish fans celebrate their win over Australia. 5 of 7 GRAHAME COX/Sunday News Irish fans celebrate their win over Australia. 6 of 7 JASON OXENHAM/Fairfax Media Irish fans celebrate their win over Australia. 7 of 7 GRAHAME COX/Sunday News Irish fans celebrate their win over Australia.

The Irish win means they're likely to top Pool C and play either Wales or Samoa in the quarterfinals.

Australia are now on a collision course to meet the Springboks in another quarterfinal, with the All Blacks potentially lying in wait in the semifinals.

The Wallabies scrum which had been performing so well of late, regularly buckled under the Irish pressure and the European scribes who took such delight in bashing the Australian pack at the last World Cup, were able to sharpen their pens and do the same all over again.

Reuters FLYING HIGH: Wallabies fullback Kurtley Beale takes a high ball over Irish opposite number Rob Kearney.

This was a far more cohesive performance from Ireland than their lacklustre and error prone win over USA last weekend and certainly much better than the four straight losses picked up before the tournament began.

Ireland openside flanker Sean O'Brien was superb last night, he's not a fetcher No 7 like the injured David Pocock, but is an outstanding ball runner and line breaker.

The Irish have regularly been a bogey team for the Wallabies, but this has to be their most significant loss to them ever.

It is also the most critical loss Robbie Deans has suffered as Australia coach in his 50 games at the helm.

Quade Cooper hardly fired a shot and while Ireland's No 10 Jonathan Sexton didn't have a big impact either, it was his forward pack that won the game.

There was huge intensity in the beginning of the game and both teams were on fire, while noise and singing among 58,678 spectators was more akin to a soccer match than a rugby one.

The first score came from a James O'Connor penalty in the 10th minute after the Australia had sustained pressure close to the Irish line.

Sexton answered back with a penalty and drop goal to Ireland over the next seven minutes.

Another O'Connor penalty completed the scoring for the half, making it the second successive game where Australia were 6-6 at the break.

Ireland took the lead again with two more penalties from Sexton in the first 12 minutes of the second half and another poor scrum in the 62nd minute led to Ronan O'Gara kicking a penalty to make the score 12-6.

A further O'Gara penalty took the Irish beyond touching distance and even though Tommy was caught just short of scoring a 98m try two minutes from time, he was able to take them far enough down field to give Australia no chance of a comeback.

Result:

Ireland 15 (Jonathan Sexton 3 pen, drop goal, Ronan O'Gara pen) Australia 6 (James O'Connor 2 pen). HT: 6-6