Petkovic acknowledged Stuttgart's style of keeping things compact and said that he wants a result to defend in the home leg next week.
"Stuttgart is a good team," Gazzetta dello Sport quotes Petkovic as saying. "They have had a few problems recently, but they are very compact and very tough on the field.
"They rarely lose at home so it will not be easy. I want a good performance so that we will know what we need to do at home."
The first leg kicks off at 6pm.