The 21-year-old looks set to be out for up to six weeks at a time when he was hoping for a run in the first team following the injury to Steven Gerrard and Lucas Leiva's suspension.
"Unfortunately, right at the end of the training session, which was five-a-side and not at all a competitive game, he turned his ankle and cracked a small bone just above the ankle in his fibia," confirmed Liverpool boss Roy Hodgson.
"That means he is going to be missing for six weeks. It is a terrible blow for Jay and us.
"He has been doing ever so well and getting closer and closer to a place in the first team. I was considering using him in this game, possibly even starting him."