Alex Oxlade-Chamberlain will miss the "vast majority" of the forthcoming season as the Liverpool midfielder focuses on rehabilitation from a serious knee injury.
Oxlade-Chamberlain was set to play a key role in the final weeks of Liverpool's campaign, which concluded with defeat in the final of the same competition, and England's trip to the 2018 World Cup.
Surgery eight days after the Roma match was a success and manager Jurgen Klopp explained it was a matter of waiting until the time was right before disclosing the severity of the midfielder's condition.
"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," he told the club's official website.
"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."
Oxlade-Chamberlain joined Liverpool from Arsenal on transfer deadline day last August for a reported £35million fee and hit a rich vein of form after the turn of the year.
He scored five times in all competitions, including a superb long-range strike in the Champions League quarter-final win over Manchester City.
"It is typical of Ox that he didn't want the news to overshadow the end of the season and, to be quite honest, we thought we could wait and tell people at an appropriate time," Klopp added.
"His surgery – which he had on the day of our second leg in Roma – has been completely successful and his recovery has started superbly well.
"But the truth of the matter is that we are preparing this season knowing he will not be with us on the pitch for competitive matches for the majority of it. If we do see him back this season it will be a bonus."
Klopp's men open their Premier League campaign against West Ham on August 12.