Liverpool captain Jordan Henderson is facing an extended period on the sidelines.
Henderson had targeted Saturday’s clash with Everton as his planned comeback date from a foot injury which ruled him out for the Reds’ last five games.
But the England midfielder’s anticipated return has been pushed back further, ruling him out of next week’s matches with Bournemouth and Stoke City.
Both Henderson and Lallana, who picked up a thigh problem on international duty, have travelled to the United States in a bid to accelerate their recoveries.
Jurgen Klopp admitted on Friday that he was unsure as to exactly when his skipper would be available for selection again in the coming weeks.
He said: “Jordan, unfortunately, had a little setback so he’s not in team training until now.
“I can’t say in this moment how long, hopefully not too long.
“We hoped he would be in training this week but he wasn’t. It doesn’t look like next week too, we have to wait.
“It’s only a question of time. It’s nothing we could do. We have to be really careful with him.
“If there was a little chance that Hendo could run and train then he would do it.
“We can’t take a risk. It’s always too long with injuries. It’s not the best time but there’s nothing else to do.
“We’ll wait for the moment when he’s back again.”
Liverpool are already sweating on the fitness of Sadio Mane ahead of Wednesday’s visit of Bournemouth to Anfield.