Klopp: Hummels to return against Stuttgart
Hummels is yet to feature for Dortmund since being handed the armband following Germany's World Cup triumph in July, with the centre-back recovering from muscular problems.
The 25-year-old has stepped up his recovery in recent weeks and Dortmund, who have lost two of their past four league games, are set to receive a boost with Hummels on track to feature at Signal Iduna Park.
Klopp said Hummels would return, though he is not ready to complete a full match.
"It looks good for Mats Hummels. He is practising without any problems," Klopp told reporters.
"We have to decide how much intensive training is necessary. He was on vacation, practised two weeks, had to pause for 12 or 13 days because he had some smaller problems. But since then he is back in training.
"Given our situation [in the league] there is a big possibility that Mats will be in the squad. But he will not play from the beginning or for 90 minutes.
"In the defence we do not have bigger problems. The next step is taking him with us. Mats has to train harder than the rest of the team, because they are regenerating. So Mats has to train a little bit more.
"But his preparation cannot be complete after that amount of time. If we had to substitute him in, that would not be a problem because he has got no issues."