Germany beat Spain to win Group B and avoid a quarter-final against England.
A Spanish goalkeeper's clearance fell straight to Klara Buhl, who scored the first goal for Germany.
Lucia could only shoot into the side net.
Popp only came back to action in March after 10 months out with a knee injury.
She scored her second goal at the Euros after coming on as a substitute in the game against the Danes.
The winner of Saturday's game between Spain and the Danes will face England in the last eight and the loser will be eliminated on the head-to-head rule.
The biggest victory in the competition's history was recorded by England when they thrashed Norway 8-0 on Monday.
There's more to come.