Petkovic happy Lazio underdogs for derby
The Biancocelesti won their last encounter, the bitter Coppa Italia Final on May 26.
"This will require mental strength, calm and concentration for the full 90 minutes. Roma are a fine squad and proved themselves with three straight victories. However, they have weaknesses and we must take advantage of them.
"This is the first day I will actually sit the players down and give them a lesson on Roma's strengths and weaknesses. We have forgotten what happened in the Coppa Italia, as need to learn about them all over again.
"We need to stay calm and approach this game with pleasure in front of our fans. We want to set a certain image for all of Europe and it is a bit of a different encounter, but it's still worth three points."