The 18-year-old is back in contention after recovering from an ankle injury sustained at Leeds United on September 12 that required surgery.
Elliott has stepped up his rehabilitation since the turn of the year and could now feature in the fourth-round fixture with the Bluebirds.
Asked how impressed he’s been with the midfielder’s recovery, Klopp told his pre-match press conference: “Very much. We have really to thank Andreas Schlumberger for that; he is our head of rehab here and was very in it, he was very patient, but Harvey was the perfect client, if you want. He did pretty much everything we told him without a question why or whatever.
“He is in a good place and is in full team training now, but we have to see what is right for him – is it right to start [or] is it right to come on? But he will be in the squad definitely for the Cardiff game and from there we go.
“Most of the things look completely natural, absolutely, really quick after a long, long period without proper team training. When you saw him the first time, you thought immediately, ‘Maybe we take him with us’ but it obviously made no sense.
“He has now to go step by step to get back to his best, but he is close. Very close.”
Meanwhile, Klopp offered a positive update on the fitness of Thiago Alcantara and Divock Origi, while Naby Keita is back in contention after returning from Africa Cup of Nations duty with Guinea.
The manager continued: “Thiago trained with us. Unfortunately, when COVID is around you always think it is the only infection or virus you can get, but he had a little chest infection so he had to step a little bit aside again.
“That’s not perfect, of course, but I expect him to be in team training today again so we will see. The injury is completely fine, he looked really good in training, but that’s how sometimes things are. We will see how we can use him for Sunday.
“Naby is completely fine. Naby came back full of energy, had a few days off as well. Came back here after the tournament full of energy and confidence, so that looked good.
“Divock, yesterday, first time team training, looked very good, but it was the first time full team training after a while, so from here we go as well.”