Former Chelsea target Niklas Sule has described signing for Bayern Munich as "a once in a lifetime opportunity."
Baba, on loan at Schalke this season, was substituted after 39 minutes of African Nations Cup match.
Defender had only returned to the BVB squad late last year after recovering from an injury picked up at the Olympics.
Borussia Monchengladbach are set for another round of contract talks with reported Manchester City and Liverpool target Mahmoud Dahoud.
Who will dominate the second half of the Bundesliga season? Which records will be broken? Five Aside takes a look at the numbers behind the headlines.
Returning from a month-long break, league leaders Bayern Munich need to be wary of a trip to Freiburg, a place that has caused them problems of late.