Klopp is unsure how long Firmino would be on the sidelines.

Liverpool boss Jurgen Klopp is unsure how long Firmino would be out for but happy midfielders Fabinho and Thiago are back.

Jurgen Klopp says Firmino's injury is not good news. [Getty]

Jurgen Klopp has revealed that Liverpool star Roberto Firmino has suffered a serious hamstring injury.

The Brazil international sustained the injury after coming off the bench at half-time in Liverpool’s 2-0 Champions League win over LaLiga champions Atletico Madrid.

The German coach doesn't know exactly how long Firmino will be out of action, saying "but it will be not now after the international break directly. We have to work on that"

Firmino had enjoyed an exceptional start to the 2021-22 campaign, scoring six goals in 11 matches in all competitions.

Speaking ahead of the Reds' Premier League match against West Ham United on Sunday, Klopp told Liverpool's official website: "Bobby is not good news with a serious hamstring injury, really unfortunate.

"We don't know exactly how long he will be out but it will be not now after the international break directly. We have to work on that."

Klopp also admitted the return of midfielders Fabinho and Thiago Alcantara is 'very important' to the team.

"Very important, you see that. Fab was clear - he was not that long out - that he can maybe go, how we decided then 60 minutes," the former Dortmund boss added.

"And swapping that with Thiago was probably exactly the right thing to do, now they should be both a big step ahead, so all good."

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