The Wales Coach has backed the Ospreys hardman to recapture the form in Rome which made him a shining light on the Lions tour to New Zealand in 2005.
Jenkins said: "Ryan can potentially be a better player than he is. We have seen him playing for the Lions when he was arguably the best player in his position in the world. There's a lot more to come from him. I'm prepared to commit to him in the belief that he will return to being a world-class player."