The Biancocelesti boss is refusing to throw in the towel on his side's chances of progression to the last four but concedes that the odds are stacked against them
Ogneyi Onazi's red card coupled with a pair of late strikes from Pierre Webo and Dirk Kuyt - the former of whom's came from the penalty spot - consigned the Biancocelesti to a likely European elimination at the Sukru Saracoglu on Thursday.
And while their coach has been buoyed by the fact that the second leg of the last-eight clash will be played out behind closed doors in Rome, their poor disciplinary record and significant deficit means their task has become all the more difficult.
"Conceding three penalties and suffering two red cards in our last five Europa League games is far too steep. It's a pity, because at this level we deserve more support," Petkovic told Mediaset Premium after the match.
"The result can be overturned as Fenerbahce will not play in front of a crowd. I don't think playing behind closed doors in the second leg will affect us.
"We are used to it as they are. It's a shame that Mauri received a yellow for a 'foul'. We must fight against all odds."
Petkovic then looked ahead to the weekend's derby della capitale against Roma in Serie A and warned his Lazio players that they can have "no excuses" for a below-par display, while providing the latest on the fitness of Miroslav Klose and Stefano Mauri.
"It's good to play in the derby next. We have so many important games left to play, so we have no excuses in terms of concentration and motivation when trying to get a result," the former Young Boys trainer added.
"Will Klose and Mauri be ready?' I don't know if they can play from the beginning. We will see their physical condition in the coming days."