Uncomfortable moments in Brussels at a North Atlantic Treaty Organisation summit on Thursday when each man appeared to battle for the firmest handshake award set the tone for a potential clash when the two sat down for the more in-depth informal talks in Italy. But it came pretty close.
The final communique is expected to be little more than six pages long, against 32 pages a year ago, with diplomats saying the leaders wanted a simpler document to reach a wider audience.
The summit of Group of Seven wealthy nations pitted Trump against the leaders of Germany, France, Britain, Italy, Canada and Japan on several issues, with European diplomats frustrated at having to revisit questions they hoped were long settled.
In his closing news conference, Italy's Prime Minister Paolo Gentiloni was unable to hide his disappointment with the lack of agreement. The G7 is united on breaking terrorist networks.
The G-7 members were still wrestling over a statement on trade and whether it would condemn protectionism, as previous group statements have. The communiqué noted the need to remove "trade-distorting practices" such as dumping, non-tariff barriers and government subsidies.
The French leader says he believes the arguments made by the six other members enabled Trump to understand the importance of that issue and the necessity the Paris agreement for the USA economy. "Meeting the Paris Agreement's temperature limitation goals is in the environmental, economic and national security interests of the United States, whereas President Trump's "climate inaction plan" is a threat to every American's health and future prosperity".
It is more obvious than ever that American business, states, universities and cities have picked up the mantle of USA leadership on climate change while over 3 million Americans are employed in the clean energy economy and solar and wind jobs are growing at 12 times the national average.
More than half a million migrants, most from sub-Saharan Africa, have reached Italy by boat since 2014, taking advantage of the chaos in Libya to launch their perilous crossings.
There is a new fault line within the G7.
"We had very hard deliberations and discussions about trade but we found a reasonable solution", Merkel said, stressing the G7 was committed to open markets.
But it was the climate file where Mr. Trump broke farthest from the G7 pack. It calls for reducing pollution in hopes of limiting global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above temperatures at the outset of the industrial revolution.
Under Mr Trump, who once called climate change a "hoax" perpetrated by China, Washington has resisted intense pressure from its partners to commit to respecting the global 2015 accord on curbing carbon emissions. That's the good news.
The G-7 marked Trump's final stop on a grueling nine-day trip through the Middle East and Europe. "Climate" did not even warrant a mention.
But with Macron seeking to cement his presidential status less than a month after his election victory and to ensure a no-mistakes policy just three weeks before a crucial legislative vote at home, the 39-year-old clearly took a different approach to some of the other leaders. We have a situation where six, or if you also include the European Union seven, are against one.
British Prime Minister Theresa May told reporters that the G7 leaders agreed that climate was a priority, despite the fact that Trump is still mulling over his final decision. Trump wasn't swayed by arguments from Chancellor Angela Merkel of Germany, France's President Emmanuel Macron and others to honor the Paris agreement, agreed upon in 2015 by nearly 200 nations to cut fossil fuel emissions and boost funding to ease the effects of global warming. The next G7 is to be held in Charlevoix, Que., and its host will be Mr. Trudeau.