Germany coach Joachim Loew on Wednesday fine-tuned his 27-man squad ahead of their pre-World Cup training camp, with Borussia Moenchengladbach's Christoph Kramer added and a trio put on stand-by.

After an inexperienced Germany side was held to a goalless draw by Poland in Tuesday's friendly, defensive midfielder Kramer, 23, comes in at the expense of Augsburg's Andre Hahn.

Schalke 04 teenager midfield stars Leon Goretzka and Max Meyer, along with Hamburg's Marcell Jansen, have also been dropped from the extended squad and put on stand-by.

"We have a few defensive midfield players who are coming back from injury or who haven't played much, so we wanted to take a few options into our training camp and Christoph Kramer has impressed us," explained Loew.

While Loew said he was impressed with Goretzka and Meyer's performances against Poland, part of the 12 who made their debuts, the Schalke teenagers will have other opportunities with Germany.

"I liked the performance of the young side and players like Leon Goretzka and Max Meyer belong to the future," said Loew.

"They are still young and still have lots of opportunities to play at big tournaments."

Real Madrid's Sami Khedira will only join the training camp after the Champions League final against Atletico Madrid on May 24 in Lisbon.

The Germans start their 10-day training camp in northern Italy on May 21 before their next friendly against Cameroon in Moenchengladbach on June 1.

There is a final warm-up match against Armenia in Mainz on June 6, the day before the German squad fly to Brazil from Frankfurt.

Germany's opening match at the World Cup is against Portugal in Group G on June 16 in Salvador.