Germany coach Joachim Low said putting his charges up against their younger compatriots has proven worthwhile.
Low's men, on a World Cup training camp in northern Italy, have been emulating match intensity by taking on Germany's Under-20 outfit.
Germany are preparing for a Group G campaign in Brazil against Ghana, Portugal and the United States.
"The real-life simulations are something very new for us," Low said.
"We've briefed them (the U20s) on certain things.
"They should put us under pressure and attack us for the first 20 minutes, then sit deep for the next quarter of an hour.
"That helps create a competitive atmosphere that we wouldn't otherwise have in training. I'm very happy they're here."
Star trio Philipp Lahm, Bastian Schweinsteiger and Sami Khedira are all under injury clouds, causing Low to turn towards Borussia Monchengladbach midfielder Christoph Kramer.
"Kramer's chances of securing a World Cup ticket are good," Low said.
"He covers a lot of ground in central midfield, is very confident on the ball and I've had a very positive impression of him."
Germany begin their World Cup campaign against Portugal on June 16.