By North-west correspondent Alex Stevens

Daniel Sturridge must answer the doubts about his fitness – or face being sold by Liverpool at the end of the season.

That is the verdict of the club’s former midfielder Didi Hamann, who played alongside Sturridge when the England international was breaking through at Manchester City as a youngster.

The former Germany midfielder says there are genuine worries inside Anfield about whether he will fulfil his potential.

Speaking ahead of Sunday’s Premier League home match against Manchester United, Hamann said of the striker: “Time is running for for Daniel to show that he is the striker to lead Liverpool’s attack in the future.

“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.”

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For the second season running, Sturridge’s campaign has been decimated by a series of injuries. He is currently out with a hamstring problem that has kept him out of the Merseysiders’ last nine matches.

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“Jurgen Klopp needs a striker he can rely on,” Hamann added. “Not only that, he expects every single one of his players to put in a shift physically.

“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.

“This is a big six months for Daniel. He has to get himself fit, play regularly and score goals.”