Frei sustained the injury during Dortmund's 1-1 draw with Bochum on Sunday, where Egyptian striker Mohamed Zidan netted the equalizer for the Black Yellows.

Dortmund doctor Markus Braun revealed that Frei has a partial tear of the outer ligament of his right ankle that will rule him out for two weeks.

The 29-year-old Swiss was not the only Dortmund casualty in the Bochum draw, as defender Mats Hummels will be sidelined for up to a month with an ankle injury as well.