The 23-year-old, who has emerged into one of Germany's brightest stars, has warned Bayern Munich that the race is not over.
"We are still positive about our chances this season. This time last year we had 10 points, and now we have 12," he told Welt am Sonntag.
"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 against Manchester City and Hannover."
Reus has scored six goals for Dortmund this season.