Joe Gomez and Dejan Lovren have handed Liverpool fresh injury problems in defence.
Gomez was expected to return to action later this month from a broken leg but has suffered a setback in his recovery which is set to require additional surgery.
Hopes of the versatile defender making a comeback in the Champions League last 16 encounter with Bayern Munich have now been dashed for the Reds.
“It is not exactly going how we want – that’s how it is,” said Jurgen Klopp.
““He needs more time. We will see exactly how we do it. There were different moments we thought we could do this or that but it will take time.
“We can not say more.”
Asked if Gomez will need to go under the knife again, he added: “I don’t know. We will see. It is possible, probably.”
The Liverpool manager is also facing up to being without Lovren for Monday’s trip to West Ham due to a recurrence of the centre-back’s hamstring problem.