Daniel Sturridge has six months to prove his fitness or face being sold, according to Didi Hamann.
The striker has spent almost as much time in the treatment room than on the pitch in recent seasons, sustaining injury after injury.
And if the 26-year-old cannot answer doubts over his fitness, Hamann says Jurgen Klopp may be forced to sell him at the end of the season.
"Time is running out for Daniel to show that he is the striker to lead Liverpool’s attack in the future," Hamann told The Mirror. "There is no doubting Sturridge’s quality, but I remember when I was at City that there were worries back then about his problems with injury."
Hamann's doubts over the England international's future at Anfield are compounded by Klopp's preferred style of play and demands of his players.
"Klopp needs a striker he can rely on. Not only that, he expects every single one of his players to put in a shift physically," he said. "There have to be doubts whether Sturridge can cope physically with the system that Klopp plays.
"If he can’t, and if his fitness problems continue, then Klopp will not think twice about bringing someone else in."
Hamann believes the striker has six months to get himself back on the field and in form.
"This is a big six months for Daniel," he said. "He has to get himself fit, play regularly and score goals."
Liverpool face rivals Manchester United on Sunday, but Sturridge will not play any part.