Franz Beckenbauer has raised concerns about the suitability of Rene Adler as Germany's number one goalkeeper for this summer's World Cup.

The 25-year-old was recently named by Germany coach Joachim Low as his number one choice, but a string of errors in recent games, including the latest in Bayer Leverkusen's 4-2 win over Hamburg yesterday, has given Beckenbauer reservations about whether he is the right man to step into Jens Lehmann's boots in South Africa.

Adler has developed a habit of racing from his line and getting caught in no-man's land, like he did as Ze Roberto equalised for Hamburg yesterday, and admitted afterwards the incident had "looked a bit stupid".

Beckenbauer was even more forthright in his appraisal.

"If somebody makes an error like that in a school team, then you would tell him to find a different sport," he said on Sky television.

"Adler is a great goalkeeper, but since he has known that he is the number one, he is making one error after the other."

Leverkusen's director of sport Rudi Voller said he could live with Adler's odd excursions both for his club and the national team this summer.

"He is just the goalkeeper that Germany needs," he said. "Rene at least takes risks and that is why he is rightly Germany's number one.

"I hate nothing more than goalkeepers who just stand on their line and play for the galleries."

Fortunately for Adler, further goals from Stefan Kiessling, Eren Derdiyok and Gonzalo Castro earned Leverkusen all three points to take them back into the race for the Bundesliga title at the BayArena yesterday.

"We have such a great team who can iron out individual errors and I hope the days soon return when I can give something back to the team," added Adler.