The striker expresses his gratitude towards his former boss as his side prepare to take on Borussia Monchengladbach in Sunday's Bundesliga encounter
The Germany forward has scored 11 Bundesliga goals so far this season, including two against his former club in a 5-0 win in September.
However, speaking to Bild, Reus was keen to praise the strength of Favre's influence on his development whilst he was under his management.
"In my career I have certainly learned the most from Lucien Favre," the 23-year-old front man revealed.
"He has supported and shaped me and worked with me on many scary details. I will never forget that."
Favre was equally effusive in returning the compliments paid by his former player, who scored 41 times in 109 games for Gladbach.
"Marco is the best player I've ever worked with," the 55-year-old trainer said.
"It is very difficult to stop him. But we must not make the mistake of focusing only on Reus."
Dortmund currently sit in second place in the Bundesliga on 42 points, 18 behind leaders Bayern Munich, whilst Gladbach are in 10th with 30 from 22 games.