Grobbelaar is a fan of the German goalkeeper, currently on-loan with Besiktas.
Grobbelaar, who made 628 appearances for Liverpool during a 13-year career that also saw him lift six league titles, three FA Cups and three League Cups, told the Mirror: “Karius is still a very good goalkeeper, a brilliant goalkeeper.
“The unfortunate thing for him is that he made two mistakes in the biggest game in football after making one mistake in his previous 33 appearances.
“But I don't think he was nurtured in the right way after what happened in Kiev.
“When he needed people to lean on there was nobody there for him.
“As a former goalkeeper and now as a coach, the first thing that must be done when a keeper makes a howler like Karius did is to go and support him.
“You ask what happened, why, how? I've watched replays of Gareth Bale's second goal over and over and it is clear to me that Loris simply took his eye off the ball.
“It was a basic error. But you don't destroy a goalkeeper over that. You tell him he's the best and you work on it every day in training.
Grobbelaar added: “It is going to be very difficult for Karius to come back to Liverpool now, after they've spent so much money on Alisson.
“I have been very impressed with Alisson. It's clear that he has got the huge personality to be Liverpool's goalkeeper.
“He's got great feet, he commands his area with authority, and he has a presence about him.
“Let's hope he can maintain the start he has made. All eyes were on him after he was blamed for conceding a goal at Leicester – but I thought he was fouled."