The 50-year-old Biancocelesti coach admits that his side have not been ruthless enough in many games so far this season but mainly attributes their stuttering form to misfortune
The 50-year-old Bosnian has been under pressure after the Biancocelesti's inconsistent start to the season, with the capital club currently in seventh place in Serie A, but argues that his side have not had the rub of the green and hopes that things will change for the better in Thursday's Europa League meeting with Apollon Limassol.
"Against the likes of Fiorentina, Atalanta and Genoa, we've just hit some bad luck," the Lazio boss told reporters.
"It's normal to ask for more from your players but, in some cases, our efforts have not been repaid. Sometimes we have come unstuck after dominating, then our mistakes have been punished.
"We have to use these results as a wake-up call. [On Thursday] we want to win. I trust that my players will have the same appetite as me.
"I do not deny that we can improve. We are all involved in this and we need to find a solution."
Petkovic also bemoaned the way in which his squad have been stretched to breaking point by injuries to so many key personnel, suggesting that the club's medical and fitness staff may be doing something wrong in terms of treatment and training.
"Bruises or smaller problems can be avoided," he mused, "and we have to analyse why we're getting so many muscular injuries."