Liverpool manager Jurgen Klopp has given a clearer indication of when his key defenders will be available.

The Reds are experiencing a shortage of central defenders, which prompted them to sign Steven Caulker on loan from QPR on Tuesday.

Martin Skrtel remains sidelined with a serious hamstring injury, Dejan Lovren is also struggling with a similar problem, while Mamadou Sakho and Kolo Toure are under injury clouds.

Regarding the crocked quartet, and the reason to sign Caulker who was on loan at Southampton, Klopp told liverpoolfc.com: "The situation is Martin Skrtel is not available for around about the next four-and-a-half weeks, five weeks.

"Then we have the problem with Dejan – it's only a little muscle injury. I think he'll be available in one to one-and-a-half weeks.

"Then you have Mama with a little knee issue – he can play, but it's not perfect and you cannot bring him three or four times in a row throughout the season.

"And it's the same for Kolo and so would mean we are always in this situation, do we have enough or not? So we thought, 'Yes, good idea'."