The German striker - who has scored six league goals this season - is suspended for the Biancocelesti's trip to Sicily and their Bosnian boss is weighing up his alternative options.
Mauro Zarate may have been a peripheral figure of late but Petkovic is considering handing the Argentinian forward a starting berth at the Stadio Angelo Massiminio.
He told Gazzetta.it: "It all depends on him. I've seen some good things from him recently, and the fact he wants to prove himself to me is very encouraging.
"I haven't got a lot of options but I hope that he who gets the spot makes the most of the occasion.
"(Tomasso) Rocchi did well on Wednesday and it's a shame he didn't manage to score.
"(Cristian) Brocchi could be ready but I'm not sure. It would be risky to play (Stefan) Radu, it's great to see him training well. He had a bit of 'flu on Wednesday."
Lazio's bid for a top-three spot has been stunted by two poor results, defeat to Fiorentina preceding a disappointing draw against Torino, and Petkovic is urging better focus from his players.
"I need the team to concentrate all the way through, to remain solid through the whole game and not just when they fancy it," he added.
"We have conceded seven goals from set-pieces and that is all down to poor concentration."
Meanwhile, Catania boss Rolando Maran shrugged off suggestions that Klose deliberately earned a one-match ban to save himself for next weekend's Roman derby.
"Do I think Lazio underestimate Catania?" he asked La Repubblica. "Understanding what their intentions are is none of my concern, but I'm sure they don't underestimate us."
Unlike Petkovic, Maran can call on his star striker, with Gonzalo Bergessio ready for action.
"Bergessio fights for every ball," he added. "He is the emblem of Catania and he consistently proves what a great footballer he is.
"We have to prove what we are capable of, too, and put in a really good performance.
"That's how we will be able to compete with Lazio, a team with no real weaknesses, one that is organised and doesn't give much away."