Liverpool defender Nathaniel Clyne will remain sidelined for a "significant period" as he works to recover from a back injury.
The England right-back last featured for Jurgen Klopp's side in a pre-season friendly at Tranmere Rovers on July 12.
He was not named in Liverpool's squad for the Champions League group stages and Klopp said the 26-year-old's omission was because he will not be available for the majority of the Reds' matches against Sevilla, Spartak Moscow and Maribor.
"Nathaniel is working hard on his rehab and we have kept a close eye on his progress, but the reality is we are looking at some time still before he is back and available for selection," Klopp told Liverpool's official website.
"I am told it will be longer than just a couple of weeks, so we will continue to monitor and assess.
"It is pretty certain he'll not be available for the majority of the Champions League group matches. If we are fortunate enough to still be in UEFA competition in the New Year he could be added to the squad then.
"The medical guys are pleased with how he is responding and Nathaniel has shown a really strong attitude, given he is not someone who is used to being out injured."
Trent Alexander-Arnold and Joe Gomez have played at right-back during the opening weeks of the season and Klopp is pleased with how the youngsters have acquitted themselves in Clyne's absence.
"What is positive for us is how Joe and Trent have stepped up and grasped their opportunities," he added.