Wolfsburg sporting director Klaus Allofs has warned that the club will need to "cope with odd decisions" in their Champions League clash against Real Madrid on Tuesday.
Bundesliga side Wolfsburg go into the second leg of the Champions League quarterfinal at Real Madrid with a 2-0 lead from the first leg at the Volkswagen Arena last Wednesday.
The Spanish giants have already predicted a memorable comeback at the Bernabeu, with Cristiano Ronaldo telling AS on Monday that it will "be a magical night" with the Portugal international asking the Madrid supporters to create a special atmosphere.
He said: "With your help the players will give the maximum on the pitch and we will go through to the next round. Hala Madrid!"
There are, however, fears in the Wolfsburg camp that not only the stadium and the Real players will play a part in the Champions League clash, but also that Hungarian referee Viktor Kassai, 40, could be influenced by the intensified atmosphere.
"We need to be wide awake. We need to get everything right," Allofs was quoted by German tabloid Bild. "We need to cope with odd decisions."
He added: "Things will happen you don't really expect yet. Take pot luck. Real are favourites. Also for the return leg. Even a 3-0 or a 4-0 [from the first leg] would not allow us to rest."