The Reds host West Brom in the fourth round at Anfield on Saturday evening (7.45pm).
And Klopp will be without the England midfielder, who has already spent much of the campaign on the sidelines.
On Lallana, the Liverpool manager said: “It’s a little tear. it’s really not a big one.
“Adam had a long injury and needs time again to adapt to the intensity of the Premier League.”
More worrying news for Reds supporters was delivered surrounding James Milner and Ragnar Klavan.
The experienced centre-half is out of tomorrow’s game with ‘a muscle issue’.
GETTY
While with Milner, Klopp added: “Milner got a dead leg in training. If he says it’s too painful for training then you know how painful it is!”
Klopp may be without captain Jordan Henderson too, as he said: “We have to think about it.”
Liverpool do have some back, though, with Daniel Sturridge and Dejan Lovren confirmed as available.
Left-back Alberto Moreno has been missing since early December.
He is training at Melwood now, but it is unclear whether he will displace Andrew Robertson, who has impressed of late.
Five players who could join Liverpool before deadline day
GETTY
“Clyne is in a good way, but still isn’t in team training”
Jurgen Klopp
Klopp said: “Alberto Moreno is back in training, what do we do? Robbo has played really well but played a lot as well.”
Striker Danny Ings is set to start for Liverpool against West Brom, as Klopp added: “He’s in really good shape, but there’s nothing to say at the moment about the lineup.
“We’ve had a few players ill, I don’t know. Ings is doing really well, the fact that we don’t send him on loan show what our plans are with him.
“Since the injury it’s been ups and downs. He’s physically completely there, I can’t remember the last session he wasn’t properly involved. It’s a good situation for him and for us at the moment.”
Long-term absentee Nathaniel Clyne, the boss continued: “Clyne is in a good way, but still isn’t in team training.”