James Milner will have to undergo late fitness tests to assess whether he can feature in Liverpool's league trip to Crystal Palace on Saturday evening.
The converted left-back missed out of the 2-1 EFL Cup fourth-round win over Tottenham Hotspur on Tuesday with illness, deputy Alberto Moreno coming back into the team in his absence.
Milner has since yet to return to full training, with Jürgen Klopp confirming that no decision has yet been made on whether or not the 30-year-old will be involved.
Reds boss: Milner ill and 'a few knocks'
Klopp, speaking in his pre-match press briefing on Friday, explained: "We have a few knocks. How it always is, nothing else [serious]."
The Reds boss revealed that Milner "was ill on Tuesday" and so "had no chance" of featuring in the win over Spurs in mid-week.
He added that the former England international "had a running session" on Thursday in order "to see how he felt" and confirmed that "it was okay."
"We have another two days [of training], but I'm not sure," said Klopp when asked about Milner's chances of playing at Palace - adding that "apart from some knocks" they are otherwise "okay."
Milner, who was sent off for two yellow cards on his last visit to Selhurst Park, has featured in eight of the Reds' nine games so far this term after watching the opening weekend win over Arsenal from the bench.
Since replacing the erratic Moreno at left-back, he has shone in his new role - but the Spaniard would be the favourite to come in were Milner to be ruled out for Palace.
'Line-up decisions no more difficult after Spurs'
Klopp will return to a more familiar line-up after he made 11 changes for the win over Spurs, but he says performances in mid-week have not necessarily given him extra decisions to make.
He insisted that he "expected" his makeshift team, which saw Trent Alexander-Arnold handed his debut and Ovie Ejaria given his first start, would "play good" and so he was not "surprised by the performance."
The German stated that his team selection is "not more difficult" than before Spurs, as he said: "It was only that they played how I expected they would, so there are the same decisions to make like before the Tottenham game."