Lucas was among those impressed by the performance levels of the 20-year-old.
"Jonjo is a young player, but he's been with us for two or three season so we have seen every day he has a lot of quality and I think he will be a very good player for this club," he told liverpoolfc.com.
"He has been very impressive in pre-season and I am looking forward to helping him when he wants me to. Hopefully he will be a great addition this season.
"My advice to him would be just to keep working hard and when he gets a chance, to try and take it.
"He has a little bit of experience already and played a few games last season, so I think he won't have a problem when he has his chance - and I will try to help him on the pitch."