The German champions are yet to reach their full potential according to the 23-year-old who is adamant Jurgen Klopp's side can still challenge for the German title
The 23-year-old, who starred in Germany's 6-1 hammering of Republic of Ireland on Friday, has warned last year's Champions league finalists that Dortmund are not going to give up.
The Germany international told Welt am Sonntag: "We are still positive about our chances this season. This time last year we had 10 points, and now we have 12. We know that we can play better, and it is only a matter of time before we are playing to our potential.
"We need to keep working hard and focus on winning our next games."
Reus has seen his involvement with the national team increase, and the attacker netted twice in Germany's victory against the Irish.
The former Gladbach player said: "I think my two goals against Ireland prove I have taken another step. I know that if I play well and work hard the coach will reward me."