I found this to be the most frustrating objective to achieve.
I don't have a German squad, but has a untradable rttf Philipp.
At first I was trying to sub him in while I'm leading. But it didn't work out. I was afraid to score or extend my lead, cause I'm afraid people will rage quit. And sometimes has to intentionlly concede to keep the other side in the game.
Now I'm trying to start Phillip. But man he is really horrible, missed every single shots. And i basically let the other side to score, so I can keep trying to get Phillip score.
But now maybe already 5 games later, only got one.