Bastian Schweinsteiger injury and 'mole' in the camp mar German advance at Euro 2012

Germany have injury concerns over Bastian Schweinsteiger (Getty Images)

A nagging ankle problem for Bastian Schweinsteiger and the continuing issue of a mole in the camp have cast a small shadow over Germany's preparations for their Euro 2012 semi-final in Warsaw on Thursday.

Experienced holding midfielder Schweinsteiger has missed some training sessions in the past few days due to an ankle injury picked up earlier in the year and his performance in the tournament has so far been below expectations.

"He has a problem and obviously it is best when no player has a problem," the Germany captain Philipp Lahm said. "It is OK when you miss a training session but when you need to sit out several then it is not that easy."

"But I am not too concerned. Bastian knows his body inside out, he is experienced and he will be able to deliver on Thursday."

"We need fit players, so much is clear," said Lahm when asked whether Schweinsteiger would play even if not fully fit. "We cannot have three or four per cent missing. We have depth in the squad and that gives you peace of mind. But clearly it would be good if Bastian Schweinsteiger could play on Thursday."

Germany made four changes to their line-up for their 4-2 quarter-final win over Greece on Friday from the side that started their final group game against Denmark but looked even sharper.

Preparations for their fourth straight semi-final in a major tournament have also been hit by revelations that a mole has been leaking the line-ups for group games and their quarter-final match against Greece to the media hours before the start.

The Germany coach, Joachim Löw, has said it was none of his players but did not rule out the possibility that the "Deep Throat" could be someone they talked to, from friends and wives to maybe agents.

Lahm said the issue had again been raised with the players and that the culprit was causing some damage.

"Everyone should be aware that it is normal for a player to tell his wife, girlfriend or agent whether they will play once they find out but you cannot reveal the line-up."

"It is sad when this thing comes out. The whole nation is behind us and it is not an advantage when it is leaked hours before. The one who released it has a problem. He has not understood how this works.

"But we will not deploy a spy," he said. "There is a lot of quality in our squad. We have a lot of depth and that is a calming feeling ahead of the semi-finals.

"All 23 players are important. It's good to know that even those who have not played for a while are able to come in and show their international class in a quarterfinal."

After failing to come out of the group stage at the 2004 European Championship in Portugal, the Germans have made impressive progress, first under Jürgen Klinsmann and then former assistant and successor Löw.

Germany were third at the 2006 World Cup at home, lost the Euro 2008 final to Spain and finished third again at the 2010 World Cup, when they lost to Spain again in the semi-finals. Since then, Germany have won all 15 competitive matches they have played. Their seventh semi-final of a European Championship is a record.

"The team has evolved very well. No team here has won four games. We want to go to Kiev [for final]," Lahm said.

For all its consistency, the Germans have not won a title since Euro 1996, which was their third continental trophy.

"We worked hard in the past weeks and we want to go to the final and win the title. That was our aim before the tournament and it hasn't changed," Lahm said.

Löw changed his entire three-man forward line in the quarter-final against Greece, bucking the "never change a winning team" wisdom. It worked like a dream, with two of the new men, Miroslav Klose and Marco Reus, scoring in the 4-2 win in Gdansk.

"We have a top squad but every player has to prove himself anew all the time and the coach then has all options open. It's normal that those who did not play are disappointed not to have been in a quarterfinal, it would be bad if that were not the case," Lahm said.

"But they know that on Thursday things could be very different again. The important thing that is the coach can rely on all players and that is the case now. The internal competition for a place in the starting line-up is great. But all of those who play must produce a good performance, that is important."