Lazio coach Petkovic thrilled with Serie A debut win
Hernanes struck the only goal of the game.
"I was trying to push these emotions away, as it's important to keep our feet on the ground and carry on working," he said of his nerves at the first top flight appearance.
"Seeing everything we've done in the last six weeks, I expected something more so far this summer.
"The team fought hard, suffered and created, so I think we were a real team today. It is getting close to the image I have of my team.
"We also needed to shake off the Europa League game played on Thursday, but we created many scoring opportunities and were generally in control.