"To have played 50 times for Liverpool by the age of 22 shows the quality he has," said the former Reds defender.
"He has the potential to be up there with the likes of Hansen and Smith - and that's an accolade of the highest order.
"The thing that impresses me most about him is his ability on the ball. He has the composure to pick out a pass or bring the ball forward. I don't see that in a lot of centre-backs these days.
"When he first arrived he looked a bit lightweight - it reminded me of when I first broke into the team. But he's filled out and worked on his strength. He also reads the game very well for his age and can cover ground quickly.
"The thing is, centre-back is a position where you only get better with age, so there's a lot more to come from him yet."