Germany goalkeeper Rene Adler has been ruled out of next month's FIFA World Cup™ in South Africa as he is set to undergo an operation to repair damaged ribs.

"This was the toughest decision of my life," said the 25-year-old Bayer Leverkusen goalkeeper in a statement. "But it would have been simply irresponsible of me, my club and the national team to have participated in the World Cup.

"Medically speaking, it would have been possible. But the pain is so great that I would not have been able to perform at my best over the longer term both in training and during matches. In such a long and intensive tournament, that is unacceptable. You need players who are 100 per cent fit."

Having missed the last few weeks with the rib injury, Adler returned on Saturday for Leverkusen in their 1-1 draw with Hertha Berlin wearing a special protector. But an examination by Germany team doctor Hans-Wilhelm Muller-Wohlfahrt has revealed the injury is far worse than first thought.

In 2006, Adler suffered a complicated rib injury which nearly ended his career. It took a titanium plate and four screws to repair the damage.

In such a long and intensive tournament, you need players who are 100 per cent fit.

Rene Adler, Germany goalkeeper.

Germany coach Joachim Low is set to name his FIFA World Cup squad on Thursday in Stuttgart and was informed of Adler's situation on Tuesday morning.

"Of course, we are very sorry that Rene will now be operated on, but he has to have the procedure," said Low. "The coaching team will now meet to discuss who will replace Rene in travelling to South Africa and we will announce our nominations in Stuttgart on Thursday."

Former Germany striker Rudi Voller said Adler's injury is a bitter blow for the national team. "I feel incredibly sorry for Rene," he said. "His great World Cup dream has ended, but now we must accept the doctor's decision. I hope and firmly believe that Rene will be between the posts for Germany's next major tournament."

With Adler ruled out, Schalke's Manuel Neuer is set to take his place in goal for Germany's opening FIFA World Cup match in Group D against Australia on 13 June with Werder Bremen's Tim Wiese also travelling.

With Low set to take three goalkeepers to South Africa, Bayern Munich veteran Hans-Jorg Butt could be set for a surprise recall nearly seven years after winning the last of his three caps for Germany. Dortmund's Roman Weidenfeller could also be an option.