Obama jets in to Hanover for a final bilateral visit to a country that has long been Europe's biggest economy, but has in modern times punched below its weight politically, diplomatically and militarily.
During Obama's seven years in office, that dynamic has changed, with the US president making the German chancellor – among European leaders at least – first among equals.
Both leaders have an approach to politics that is heavily analytical, leading aides to talk about a relationship that is cerebral and without comparison.
"I consider Angela one of my closest partners and also a friend," Obama told Germany’s Bild newspaper, laying on the compliments on the eve of his trip.
"I've worked with her longer and closer than any other world leader, and over the years I've learned from her," he said.
"She embodies many of the leadership qualities I admire most. She's guided by both interests and values."
Today, while the United States has a "special relationship" with Britain and France is America's "oldest ally", Germany has become Washington's "indispensable partner".
Obama is ostensibly visiting to attend the Hannover Messe, a trade fair that underscores Germany's commercial prowess.
One of the headline goals of the trip is to advance negotiations on what could become the world's biggest free trade agreement, the Trans-Atlantic Trade and Investment Partnership (TTIP).
Both sides say they aim to see it finalised, at least in its broad outline, before Obama leaves office in January.
However, Merkel's economy minister Sigmar Gabriel cast doubt on those ambitions Sunday, warning the deal "will fail" if the US refuses to make concessions in the protracted talks.
"The Americans want to hold fast to their 'Buy American' idea. We can't accept that. They don't want to open their public tenders to European companies. For me, that goes against free trade," Gabriel, a Social Democrat who is also Germany's deputy chancellor, told business newspaper Handelsblatt.
His comments came a day after tens of thousands of people marched against the US-EU free trade deal through the streets of Hanover, where Obama and Merkel are to open what is billed as the world's largest industrial technology fair Sunday night.
The US president will wrap up the visit on Monday with a keynote speech designed to frame his vision of transatlantic relations, followed by a meeting with Merkel and the leaders of France, Britain and Italy.
For Obama, the trip will be an opportunity to burnish his legacy and politically embrace Merkel, whose fortunes at home have been hit by her handling of the migration crisis.
Critics say her openness to refugees only sped the vast flow of people coming from Syria and beyond.
"I believe that Chancellor Merkel's approach to the refugee crisis – and that of many Germans – has been courageous," Obama said, voicing an opinion heard less often in Germany than Merkel would like.
Despite the diplomatic niceties, the relationship between Obama and Merkel has also been rocky.
They have frequently clashed, most notably over fiscal policy. Merkel has backed austerity as the remedy to European sovereign debt crises, while Obama came down firmly in favour of public investment to buy a way out of the morass.
US-German relations hit a low in 2013 when it became known that the US government had been tapping Merkel's phone.
But officials point to the Ukraine crisis and the downing of flight MH17 as a turning point that helped both leaders begin to work in tandem.
Merkel, according to Obama, "has been essential to maintaining European unity against Russia's aggression against Ukraine."
(FRANCE 24 with AFP)