Young midfielders Elliot Simoes and Callum Styles got the goals in the game which had no media presence.
Head coach Gerhard Struber said: “We won against massive opponents and I’m especially happy about the performance from the boys. We had a very good structure against the ball, a very good self-motivation from every player and a balance between heart and brain.
“For me, it is a good feeling that I can see many boys can make a good performance and I am happy. It is very important for me and my boys that this is only a friendly game and it is a good feeling; we have high-intensity values and it is a good signal for me that we are ready for the start.
“The tactical and physical values today are going in the right direction – this gives me a good feeling for the next task. What we’ve worked on in the last few days has helped to make this a difficult task for the opponent.”
The Reds are due to restart their Championship campaign at QPR on June 20.