The Biancocelesti boss is concerned with the forward who is currently struggling with fitness issues, but he remains confident that his side can be successful against The Old Lady
Suffering from a cold, the experienced Germany international had already missed his country's draw against Netherlands.
And according to the Bosnian boss, it looks as though he will not have fully recovered in time for the clash against the title holders.
“We have to be cautious with Klose,” the tactician stated. "He’s not very well at all. He’s got a cough and, although he has trained, he’s not in top shape,” the 49-year-old tactician explained to reporters.
But the Biancocelesti coach is confident of causing an upset at Juventus Stadium on Saturday, having took three points off their fiercest rivals in a thrilling 3-2 victory last weekend.
He continued: “Juventus are favourites for the Scudetto, but we have the ability to win in Turin.
“In order to do so, we will have to play like we did against Roma, but then add another 20 to 30 per cent.
"That’s the only way to beat them in their stadium.”
Petkovic admitted, though, if they are to get a result which would end their four-game losing streak against the Bianconeri, then, his side need to be more focused - especially at free-kicks and corners.He added: “We are struggling to defend set-pieces,
“We have to improve our concentration and individuals need to take more responsibility.”
Lazio sit fifth in Serie A. Their match at Juventus on Saturday kicks off at 18.00CET.