The midfielder is on-loan at Dortmund from Real Madrid and after a difficult start, is now beginning to prove his quality.
After scoring in the 3-0 win, Reinier said: "I've worked hard.
"My family and I have never stopped believing in this. I'm happy it worked out today."
Reinier is yet to start in the Bundesliga for BVB and his loan runs to the end of next season.