Alex Oxlade-Chamberlain is likely to miss the whole of the forthcoming season.
The extent of the knee injury suffered by the Liverpool midfielder during the first leg of their Champions League semi-final against Roma in April has now been revealed.
The 24-year-old sustained what has been described as multiple ligament damage in a tackle and underwent successful surgery eight days later.
He will not need to go under the knife again but faces a long rehabilitation programme before he will be able to return to competitive action.
A statement from Liverpool read: "The estimated length of his lay-off was not revealed at the time at the request of Oxlade-Chamberlain, who did not want the news to distract from the Reds' ongoing Champions League run and the excitement surrounding it."
The news will come as a major blow and a shock to Liverpool supporters, with Oxlade-Chamberlain among their star performers during the latter stages of last season.
Manager Jurgen Klopp told liverpoolfc.com: "It feels like now is an appropriate time to tell people that for Ox this coming season will be about focusing on recovery and rehab.
"We have known this from pretty much the day after he got the injury and after the successful surgery, we were sure of it. I hope everyone treats this information responsibly.
"There has been no change, no setback - it's exactly on the schedule we expected and planned for. The new information is that we're now giving more detail publicly.
"It is typical of Ox that he didn't want the news to overshadow the end of the season and, to be honest, we thought we could wait and tell people at an appropriate time."