By ESPNSTAR.com staff
Lazio are heavy favourites to progress to the Europa League group stages after they comfortably beat Mura 2-0 in Slovenia during the first leg of the play-offs tie.
The Biancocelesti go into the second leg in a buoyant mood following their winning start to the Serie A campaign but Petkovic is wary of the negative effects of overconfidence and wants his team to do a professional job against Mura and avoid being at the receiving end of an upset.
"I expect character from the team. The psychological approach will be crucial, as we must win and do so convincingly," he was quoted as saying on Lazio's official website.
"We are the favourites tomorrow, but we have to prove on the field that we deserve that title."
To prove his point, the 49-year-old highlighted the example of Serie A rivals Inter Milan's struggles with unfancied Hadjuk Split, when the Croatian side gave the Nerazzurri a scare after they fought back from being 3-0 down in the first leg to narrowly losing 3-2 on aggregate in the second leg.
"Inter were favourites in the last round, but they ran into huge problems with Hajduk Split," Petkovic added.
"This is not the first time that Lazio have played in the Europa League, so we have the experience to know that playing in an important match means focusing on the mental attitude, because physically we are ready.
"Miroslav Klose will rest until tomorrow [Thursday], then I'll decide on the line-up in the morning. I will be rotating the squad to a certain degree."
The former Sion manager was under immense pressure after a series of defeats during pre-season but Petkovic has since revealed that he was never flustered about the losses.
"Pre-season was not a disaster.
"It had some positives. The only negative aspect was the defeats, which arrived even after we dominated."
Michael Ciani, who recently joined Lazio from Bordeaux was also given Petkovic's endorsement.
Speaking about the new Lazio recruit, Petkovic said: "He could help this team to make the step up in terms of quality and finally I'll have alternatives in that role."
Petkovic took over the helms at Lazio in June this year after previous Lazio manager Edoardo Reja quit the club during the summer despite leading the Rome based outfit to a respectable fourth place finish in the Serie A.