Union Berlin fullback Robin Gosens has fired a warning at Real Madrid.

Union open their first ever Champions League campaign with a clash at Real Madrid tomorrow night.

Gosens said: "If you are not careful, it risks becoming a very bitter experience. Amazement and fear are the two things we don't need. We will need self-confidence and to have fun. At best, this combination should bring us to play a huge game.

"Playing in that stadium is a unique experience. Not everyone is allowed to do this. I think two things are important: first, don't forget to enjoy the game. But we must not forget that they are 90 minutes of football in which even the little ones can hurt the big ones.

"There are numerous examples of this in football. And we should approach the match with this intention."