"He’s doing really well. He is very strong and came back well from his injury when others had a chance to take his place.
"The next step now is to build a side around him but it’s important to find a centre-back partner who is not like him. They can’t play the same way.
"They have to find someone who has the ability to defend but doesn’t defend like him.
"The two guys in the middle of the park should never be identical. Both should be strong, sure, but maybe a guy who is on a different scale technically whereas Rudiger is a guy who says 'don’t mess around with me.'"