Despite resuming light intensity training back in September which Jurgen Klopp deemed a "big step" forward, Clyne has now gone under the knife.
The English media reported on Monday evening that the England global has undergone corrective back surgery on an issue that has plagued him for months, and will continue to do so with the 25-year-old now set to miss another three months of action.
Last season he played all but one of Liverpool's 38 Premier League games, making a total of 41 appearances in all competitions.
Klopp had earlier said on Clyne's injury, "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". "At this stage we haven't seen Sadio yet to properly assess the extent, but what is clear is that we will have to stay on top of this for the rest of the week and make sure we are careful in how we look after him", explained the German manager.
The 26-year-old has not played since the problem first emerged in pre-season.
Now, it has emerged that Clyne "underwent minor corrective surgery on his back on Monday and that he will now be unavailable to Klopp until February at the latest".
"We showed him to specialists all over the world".
The former Southampton right-back is expected to return in time for the run-in to Liverpool's season, with youngsters Joe Gomez and Trent Alexander-Arnold having alternated at right-back in his absence. It is pretty certain he'll not be available for the majority of the Champions League group matches.