Kirchhoff, on loan from FC Bayern München, was injured in an innocuous challenge from youth player Marcel Sobotka on Sunday and had to cut short his participation in training.
Heldt not worried
The former 1. FSV Mainz 05 man was bandaged heavily following the incident and although claiming it was not a serious injury, has now returned to Germany for treatment.
"Jan's ankle is in a cast and he needs seven days of rest," explained sporting director Horst Heldt. "We had thought to keep him here, but in view of the scan results and a conversation we've had, we've decided it makes more sense for him to go home. He is looking at about 14 days before he is back in action. We're not worried. He's integrated himself into the team and been welcomed warmly. We're not worried."
Kirchhoff will play with the Royal Blues until the end of the 2014/15 season after finding his playing time limited at his parent club.