Germany coach Joachim Low has called four uncapped players into his squad to face Chile in an international friendly next Wednesday while Bastian Schweinsteiger returns from injury.
Hamburg forward Pierre-Michel Lasogga, Augsburg's Andre Hahn, Freiburg's Matthias Ginter and Shkodran Mustafi of Sampdoria have all earned calls to a 21-man squad which also includes vice-captain Bastian Schweinsteiger for the first time after a recent injury lay-off.
With only three months to go before Low names his World Cup squad, the naming of four newcomers shows he is still undecided about his final 23 picks.
"In view of the World Cup, we cannot make any compromises," Low said. "We've got to do everything for success now and I've held lots of one-to-one talks with my players in recent weeks.
"Many of them, even key players, are still carrying knocks or are just back from injuries and they are not yet in a rhythm.
"We now have a chance to act and work on solutions and alternatives for the worst-case scenario.
"That is why we've called up some fresh faces, who have been playing consistently well for their clubs lately. Our aims are fully focused on our first World Cup game on June 16 because we've got to have hit our peak when we face Portugal.
"We will only manage that when all of the players we will work with in Sudtirol in two and a half months' time are fit, both physically and mentally."
Mustafi and Ginter have both been promoted from the under-21s while Lasogga will be seen as an alternative to Mario Gomez, who has only just returned to action for Fiorentina after a five-month lay-off.
Schweinsteiger is also back for Bayern Munich after injury and he has been called up to pick up some more match practice for the national team.
"He's an absolute world-class player who can make the difference in Brazil," Low said.
"I know how hard he is working on being in optimal condition for the summer and I am counting on him showing his leadership qualities with us."
Low will otherwise be using Wednesday's friendly match, which will be played in Stuttgart, as a chance to face a South American team ahead of the World Cup.
"They're going to be uncomfortable opponents for us at the start of this World Cup year," added Low.
"We want to test a few variations against them because we don't have much more chance to do so."
After facing Chile, Germany next face Poland in Hamburg on May 13 before facing Cameroon in Monchengladbach on June 1.
Armenia are the opponents five days later in Mainz, the day before Germany fly out to Brazil.
The full Germany squad
Goalkeepers: Manuel Neuer (FC Bayern München), Roman Weidenfeller (Borussia Dortmund)
Defenders: Jerome Boateng (FC Bayern München), Matthias Ginter (SC Freiburg), Kevin Großkreutz (Borussia Dortmund), Marcell Jansen (Hamburger SV), Philipp Lahm (FC Bayern München), Per Mertesacker (Arsenal FC), Shkodran Mustafi (UC Sampdoria), Marcel Schmelzer (Borussia Dortmund)
Midfielders: Lars Bender (Bayer 04 Leverkusen), Mario Götze (FC Bayern München), Andre Hahn (FC Augsburg), Toni Kroos (FC Bayern München), Mesut Özil (Arsenal FC), Lukas Podolski (Arsenal FC), Sidney Sam (Bayer 04 Leverkusen), Andre Schürrle (Chelsea FC), Bastian Schweinsteiger (FC Bayern München)
Strikers: Pierre-Michel Lasogga (Hamburger SV), Miroslav Klose (SS Lazio)