Kahn says it is only a matter of time before Wirtz begins to match the performances enjoyed with former club Bayer Leverkusen.
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He told Sky Deutschland: "It's not surprising if you look at where he comes from.
"At Leverkusen, everything was very protected. It was an environment he knew. He was a real superstar there.
"I have great respect for players who say, 'I'm taking the plunge now'."
Patience from everyone will be key, says Kahn: "That's the intelligence of a club: 'I don't buy a player at this age for this much money, I don't immediately demolish him and destroy him'. They give him time."