The versatile wing-back is optimistic his German side can attain a good result in the home game against the Catalans, but feels it will be very difficult to progress
Castro is hopeful of recording a positive result in the first leg at the BayArena on Tuesday, but realises that the Werkself await a tough task in the return at Camp Nou.
"Barcelona are the clear favourites, but we will try to make things as difficult as possible for them. We might be able to get a good result in the home game, but it will be very difficult at Camp Nou," Castro said to COMRadio.
"In Tuesday's home match, things could be more difficult for them if we have some luck, and if Barcelona are having a bad day.
"We are a team that likes to play football. We're not interested in making a lot of fouls. We always want to play football and win."
Tuesday's match at the BayArena kicks off at 20.45CET.
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