Shane Horgan has brought jubilant Ireland crashing back down to earth by warning: "We're not the finished article."

The Irish opened their November international series with a dazzling 32-15 mauling of shambolic South Africa, suggesting they may at last be ready to realise their vast potential.

Victory over Australia at Lansdowne Road on Sunday would give them another prized — and rare — southern hemisphere scalp as the countdown to next year's World Cup continues.

And powerful Leinster winger Horgan, who was in wrecking-ball form against the Springboks, insists expectation demands their scintillating form is maintained.

"Our performance against South Africa was up there but we're certainly not the finished article. There's a long way to go for this team," he said.

"We gave away points in the second half that we shouldn't have done. On very few occasions did they pose a threat to us. For that reason, it was disappointing that we gave away the points away we did.

"We had opportunities to score more tries. It was a good win but it's only the starting block. There's more to work on. We're not patting each other on the back just yet.

"Wins like this over the southern hemisphere have been rare for us. When I first started playing for Ireland, they just didn't happen.

"But there's an expectation on this team that's developed over the past couple of years.

"We were favourites to beat South Africa and I don't know the last time Ireland were favourites against the southern hemisphere. It's a healthy position for us to be in.

"But with that comes responsibility. We have to perform and get results against these teams. We have to beat them as it's no longer good enough to lose narrowly."

Ireland's dynamic display against the Springboks might see them installed as favourites against a Tri-Nations team for the second week in succession, even though the Wallabies are at close to full strength.

"We'll know a little bit more about where we after we've played Australia. It's still early in the season and it's a huge season and a big year," said Horgan.

"Australia will be a huge Test for us. They play a very different game to South Africa. They give you less chances of making line breaks.

"They're very solid in defence and they defend differently from South Africa. They're very smart and are very well prepared. They know what you're going to throw at them."

One of the criticisms frequently levelled at Ireland was their inability to compete with rivals in terms of size, but they dismantled the bigger South Africa pack on Saturday.

Horgan is delighted his side are no longer bullied but insists there is still more work to be done in the gym between now and the World Cup.

"We're developing and are no longer playing with the fear of being bullied by opponents. But we're still not quite up there but we plan to be up there for the World Cup."