The centre-back picked up the injury in Germany’s 1-0 international friendly win over England on Tuesday and have undergone series of tests on Wednesday to determine the extent of the knock.
Dortmund initially hoped that the injury would not be too serious, but the 24-year-old has now been diagnosed with a broken metatarsal that will keep him out of action until halfway through January.
Consequently, hummels will miss out in this weekend’s Bundesliga match against leaders Bayern Munich as well as the Champions League games at home against Napoli and away against Olympique de Marseille.
Also, Marcel Schmelzer will be absent for three weeks due to a calf problem while away on international duty with Germany as well.
The left-back will surely miss the matches against Bayern and Napoli, but could be in quick shape in time for the clash with Marseille on December 11.
Dortmund were already without the injured Ilkay Gundogan and Neven Subotic for this weekend’s match at the Signal Iduna Park.