He reckons the centre-half has been a ‘rock’ at the back since getting into the side in place of the injured Mark Connolly.
Kewell says the former Ipswich player is keen to improve and has been ‘excellent’ since coming into to the side on August 26 for their 3-0 win away against Swindon Town and has played every game since.
The 22-year-old Welshman’s displays this season have earned him a two-year extension to his contract, which he signed this week and means he will remain a Red until the end of the 2020 season.
He said: “Josh wears his heart on his sleeve and he was disappointed that he wasn’t (in the team) at the start.
“Like I’ve said to everyone, you work hard in training, your opportunity will come.
“His opportunity came through a mishap to Mark Connolly and to be fair he took it and has been excellent ever since.
“He’s been our rock at the back, he’s been strong, he’s been winning headers, he’s been playing out.
“He’s had one little slip in one game that he had (against Notts County), other than that, I can’t fault him; he’s been perfect and hopefully it continues.”
Kewell added that Yorwerth is keen to progress further with his game.
The Champions League winner said: “He’s got a good head on his shoulders, he wants to play football, he wants to learn, he wants to go and be better, we’re working on that.”