Speaking on DSF television, Beckenbauer pinned the blame for Bayern conceding a last-minute equaliser to Stuttgart in their 2-2 draw at the weekend on Rensing.

The 24-year-old goalkeeper flapped at a corner and fell out of position when Sami Khedira fired the ball into the roof of the net, a goal which cost Bayern top spot going into the winter break.

"When the goalkeeper goes out, he has got to collect the ball," said Beckenbauer.

"The way he wanted to punch the ball away is amateurish.

"He is a great goalkeeper on his line, but he has got to learn how to go out and punch the ball.

"He is lacking in that department and, to play at Champions League level, you need to have a top goalkeeper."

Rensing still has plenty of time to learn, though, and Beckenbauer does not feel it would be right to sign a new, more experienced goalkeeper in the meantime.

"We have just got to be patient with him," added Beckenbauer.

"Iker Casillas, who is now a star goalkeeper at Real Madrid, made mistakes at the start too.

"He would even punch the ball into his own goal. They had patience and let him keep playing, and now he is one of the best goalkeepers in the world.

"Rensing will become that too."