The Swiss forward has been ruled out for Liverpool since last month due to a calf issue, but is not far off resuming work at Melwood.
“It’s just taken a little bit longer, that’s how it is,” the manager explained to Liverpoolfc.com onboard the team flight to Genk on Tuesday.
“We expected him to be back this week, but now he is not here obviously so we will see when he can be back.
“It’s a really specific thing for him. It is not a big thing, it just takes a little bit longer than we expected and that’s all.”