Malcolm Turnbull and other G20 leaders are expected to find common ground on fighting terrorism and promoting economic growth when they meet in Hamburg this week.
But with US President Donald Trump making his debut at the summit, bringing with him his "America First" approach, there's likely to be less agreement on free trade, the global steel industry and climate policy.
The leaders, protected by 21,000 police with water-cannons and dogs, will be met by tens of thousands of protesters in host Chancellor Angela Merkel's birthplace, arguing capitalism and globalisation are not delivering for the poor and marginalised.
Mr Turnbull said on Tuesday it would be a "unique opportunity" for Australia to engage with some of the largest and most advanced economies in the world.
He will discuss combating terrorism, the benefits of trade and open markets, energy and sustainable development, women's participation, digitalisation and "ensuring the benefits of a strong economy can be shared by all".
Australian Strategic Policy Institute executive director Peter Jennings told AAP wide differences between leaders such as Mr Trump and Ms Merkel would make it difficult to agree on parts of the final leaders' communique.
"Where they have commonality would be on economic growth," he said.
"Fighting terrorism is high on the agenda and they will all be able to agree about that."
The German leader, who faces elections in September, has expressed her disappointment with the US decision to pull out of the Paris climate accord and become more protectionist on trade.
Mr Trump has telephoned her ahead of the summit, telling her he looked forward to making it a success and wanted to work with her on issues such as climate, trade and global steel overcapacity.
Mr Turnbull, who will meet with Ms Merkel on the eve of the summit on Thursday, is expected to be a key ally as she seeks to overcome Mr Trump's political parochialism.
After the G20 meeting, Mr Turnbull will head to France to meet with President Emmanuel Macron and formally open the new Australian Future Submarine office in Cherbourg.
Mr Turnbull will also have an audience with the Queen in London and meet Prime Minister Theresa May and senior members of her government.
The prime minister will also pay his respects to the victims of last month's London Bridge terrorist attack.
Two young Australian women, Sara Zelenak and Kirsty Boden, died in the attack.
