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Editor’s Note: Professor Matt Qvortrup is author of “Angela Merkel: Europe’s Most Influential Leader,” published by Duckworth. The opinions in this article belong to the author.

(CNN) —  

Angela Merkel can teach the American President a thing or two about international diplomacy.

The year was 2005, and former British Prime Minister Tony Blair was still a political superstar on the international stage.

The then-leader of the German opposition, Angela Merkel, was a generally underestimated politician who was destined to become leader of her country. Blair knew this. That is why he met her. But Merkel did not stick to the polite platitudes. She cut straight to the chase.

“I have 10 problems,” said Angela Merkel – and then began to list them, starting with her own lack of charisma. This was how Jonathan Powell, Tony Blair’s chief of staff, remembered Merkel’s first encounter with her British colleague.

Merkel was humbled by the task of becoming Chancellor of Germany – the most powerful political position in Europe. And she was not too proud to ask Tony Blair for advice.

Blair was happy to help; getting a friend in Berlin was rather useful before the important negotiations over the European Union budget the following year.

Blair magnanimously agreed that Thomas de Maizière, Angela Merkel’s chief of staff, would shadow his British counterpart and learn the skills of job.

Blair believed he had found a friend and an ally. But that alliance only lasted until the EU summit. Merkel outmaneuvered her British colleague. Blair was fuming but could do nothing. All is fair in love and war and EU summits.

Other leaders have similarly learned that Merkel’s disarming charm and humility count for little at the negotiating table.

Donald Trump – who excels in posturing – has hitherto shown little inclination towards humility. Even more a novice at the game than Merkel was, he is unlikely to ask for advice from his fellow leaders.

The German Chancellor has always been an avid listener. When she, as minister of the environment, negotiated the Berlin climate deal, she turned to the Indian diplomat Kamal Nath, who advised her on how to get a deal.

She found common ground with Asian countries and used this to get an agreement that was good for German engineering firms specializing in green energy.

Throughout her career as a politician, Merkel’s skill has been to listen to advice from other parties and to wait patiently for signs of a breakthrough. This means that she has always been able to get deals that put “Germany first.”

In this regard, her priorities are not that different to Donald Trump’s. It is just that Frau Merkel presents herself as an internationalist – and then gets deals that first and foremost benefit German businesses.

Many other politicians – and none more so than Trump – like to make bold claims, to act fast and think much later. Not so with Merkel.

The Germans famously have invented the word Merkeln to describe the patient, slow and almost procrastinating negotiation style of Angela Merkel. This is not always a compliment.

But it has proved to be an efficient weapon against the larger-than-life macho men with whom Merkel has to deal as Chancellor of Germany and presently as host of the G20 meeting.

Over the weekend, we can expect Angela Merkel to be a polite, attentive and relaxed host. This is how she dealt with Blair, with a succession of Greek Prime Ministers and with Russian President Vladimir Putin following the annexation of Crimea in 2014.

On all these occasions, Frau Merkel has been able to outsmart male opponents who have declared their hand too early.

Part of this strategy is due to meticulous preparation and planning. In the days leading up to the summit – while Donald Trump will no doubt be busy sending tweets about his opponents – Angela Merkel will most likely be forging alliances and deals.

Donald Trump could learn a thing or two about strategy from his German host.