Defender Holger Badstuber has said Germany's centre-backs can ill afford a mistake against Greece in Friday's Euro 2012 quarter-finals with Arsenal's Per Mertesacker waiting in the wings.
The 27-year-old Mertesacker missed the last three months of the season after tearing ankle ligaments playing for the Gunners in February and Mats Hummels is expected to continue in his place against the Greeks on Friday in Gdansk.
Bayern Munich's Badstuber, 22, and Borussia Dortmund's Hummels, 23, both came through Bayern's Academy, although neither played in defence at the time, and have risen to become stars of the Bundesliga and now the national team.
With just 30 caps between them, the pair are forging an impressive centre-back unit, but Mertesacker's impressive tally of 81 internationals means there is plenty of experience waiting to take over, if need be.
"Per is an important element of the group, he is a popular and very experienced player," said Badstuber on Tuesday having played 19 of Germany's 25 matches since the last World Cup.
"That is what counts and anyone who says his era (in the national team) is over is a complete idiot.
"Per has had a difficult last six months and his injury took a long time to heal.
"Before the Euro he didn't play a real game and that made things difficult for him."
Germany coach Joachim Loew has said he opted for Hummels and Badstuber, in preference to Mertesacker, because the pair had both held down regular spots for their respective clubs and is pleased with their development so far.
Midfielders Bastian Schweinsteiger, Mesut Ozil and defender Lars Bender all sat out training on Tuesday purely to aid recovery after Sunday's 2-1 win over Denmark.
Having created an upset by beating Russia to qualify for the quarter-finals as the runners-up in Group A, Greece are bidding to emulate their Euro 2004 winning squad and Badstuber says the Germans must be on their guard.
"We have every reason to be self-confident against Greece, but they will be tough to play against and will try and hit us on the counter," said the Bayern Munich defender after Germany won all three Group B matches.
"It would be a primary error for us to go into that game thinking we have already won, that would be a major mistake.
"They aren't seen as one of the game's powerhouses, but have already beaten Russia and they were one of the favourites."