Sancho came off the bench to replace fellow youngster Jacob Bruun Larsen with 16 minutes left of the Matchday 5 game at the Signal Iduna Park with his team 5-0 up.
Rather than resting on his teammates' laurels, the 18-year-old pressed on, scoring Dortmund's sixth with five minutes left before teeing up Julian Weigl to wrap up a spectacular win that left Reus purring.
"It's just crazy. I think it's incredibly important that he comes off the bench and does so well every time," said the BVB captain, who had been the chief architect of his team's emphatic victory.
"When our opponents ease off a little and Jadon comes into the game, then he's a weapon for us every single time. We're happy to have him up our sleeve and he always gives us a boost."
When you factor in all his five league appearances this season have come from the bench, the former Manchester City youth academy prospect has been involved in a Dortmund goal every 25.5 minutes on the pitch.
Watch: Hear what Sancho had to say about his first Bundesliga goal!
"We have great quality on the bench," said BVB's former captain and current head of the licensed player division Sebastian Kehl.
"The players that come on show a good attitude and mentality. Each one fights for his place."