Marco Reus suffered an adductor problem towards the end of the 2015-16 campaign and consequently missed Euro 2016.
Dortmund were initially hopeful he would be back in action by September, but the 27-year-old Germany international endured a minor setback that delayed his comeback.
Nevertheless, Reus is now one step closer to returning to Bundesliga action after joining his team-mates on the training pitch on Tuesday.
The former Borussia Monchengladbach star took part in a number of exercises with the rest of the squad before completing an individual session.
Reus last featured for BVB in the DFB-Pokal final defeat at the hands of Bayern Munich on May 21.