Adam Lallana was absent from Liverpool training at Melwood on Thursday, with the midfielder unlikely to be in the squad for the weekend's clash with Sunderland.
The Reds welcome David Moyes' side to Anfield on Saturday looking to get back to winning ways after a goalless draw against Southampton a week ago.
Lallana missed out on that trip to face his former club at St Mary's with a groin injury sustained while on international duty with England and the 28-year-old is still struggling with the problem.
Without him, the remainder of the first-team were all involved. - including Philippe Coutinho, Roberto Firmino, Jordan Henderson, Joel Matip, Dejan Lovren, Nathaniel Clyne and James Milner.
But Academy youngsters Ovie Ejaria, Ben Woodburn and Trent Alexander-Arnold all joined in, with Tuesday night's EFL Cup quarter-final against Leeds United potentially in mind.
Wijnaldum in for Lallana?
Lallana could too be absent for that, Klopp before the Southampton game indicating that the Reds' No.20 could be sidelined for "possibly the two or three games."
If he does miss out against Sunderland as expected, Georginio Wijnaldum is the favourite to keep his role in the centre - with the possibility for Klopp to name an unchanged starting eleven for the first time in 41 matches.
Wijnaldum replaced Lallana last time out, joining captain Henderson and Emre Can, with the attacking triumvirate of Coutinho, Firmino and Sadio Mane ahead of them.
But Klopp also has the option of dropping Coutinho deeper into the advanced central midfield role that Lallana has thrived in, with Daniel Sturridge and Divock Origi possible alternatives to lead the line over Firmino, who could move out wide.
The manager gave nothing away as to his intentions for his starting line-up when addressing the media at his pre-match briefing on Thursday, suggesting that there was still plenty of time between then and Saturday's game for things to happen to impact his decisions.