The youngster signed for the Londoners earlier this summer and Mourinho believes that he has a lot of similarities with Ashley Cole.
Speaking to Football London, the Portuguese manager said: “I think Ryan can play as a left-back. probably the left-back in the last decade was Ashley Cole, in spite of him being from two enemy clubs, but he was fantastic. But Ryan has lots of similarities with Ashley, and he can learn how to defend. In the future I think he can be (a left-back) but in this moment he is not ready to play as a left-back.