Assistant coach Dwight Lodeweges scribbled down a teamsheet with captain Van Dijk up front alongside Luuk de Jong and it turned out to be an absolute masterstroke.
"I received the letter from (assistant coach) Dwight Lodeweges, ' Koeman said after the game".
Holland join Switzerland, England and hosts Portugal in the inaugural four-team finals next June.
The late point earned sent Netherlands top of their Nations League group ahead of France, with Germany ending bottom, relegated.
However, their quick young frontline, nicknamed "the moped gang", looked promising and lived up to their tag as 22-year-olds Werner and Sane, plus Serge Gnabry, 23, frightened the Dutch defence with their speed, especially in the first half.
"But when it came up at 2-0 I said no, we are not going to do that now".
After missing out on qualifying for the finals of both Euro 2016 and this year's World Cup, Van Dijk said the priority is to get the Dutch to the Euro 2020 finals.
"We had trouble with that, it is something we have to learn from".
"We should have scored the third goal, then you run the game down, but it didn't work out like that".
Netherlands' players celebrate with the fans after the UEFA Nations League football match Germany v the Netherlands in Gelsenkirchen on November 19, 2018.
Despite finishing the year with a 3-0 win over Russian Federation last Thursday and a draw with the Dutch, 2018 has been a nightmare year for the Germans.
"Germany are, of course, a good team, they played well between the lines and with strikers that had a lot of movement".