The coach admits that their clash with Fenerbahce on Thursday will be more difficult because of the sanctions placed on them by Uefa
The Biancocelesti trail the Turkish outfit 2-0 from the first leg and have to play the return game in an empty stadium after Uefa found their fans guilty of racist abuse during a game against Tottenham earlier in the competition.
“It takes away something from our play,” Petkovic told reporters.
"We played well against Stuttgart [when the stadium was closed]. We must help each other and communicate a lot during the match."
The 49-year-old also stressed the importance of an early goal against their opponents as they seek to find a route back into the tie.
“Tomorrow we will need courage and patience, we will have to impose our game and try to score as soon as possible," he continued.
“We have a less than 50 per cent chance of going through but we have seen so many comebacks. The 2-0 is a dangerous scoreline for them.”
The coach also laughed off suggestions that Italian sides are too physical with their man-marking at set-pieces in European competition.
“I do not think it's always our fault, maybe we should play basketball and mark the area to our adversaries, without touching them,” he added.