The 22-year-old, whose £35million price tag is a record for a British player, has not played since December 28.
Kenny Dalglish: "His training is always progressing but he has not yet progressed to a game yet.
"We have said all along we have been delighted with his progress and what he has done. There have not been anything which he has done which has not been encouraging.
"Whether he will be involved on Sunday, I'm sure Fergie (Sir Alex Ferguson) would love to know, but we don't know yet.
"He might not even be a substitute - he might be going to see Boyzone."