Ivan Prtajin leaves Union Berlin to join Kaiserslautern in the second division. He played sporadically for Union Berlin last season with only 158 minutes on the field. The transfer is considered the best solution for all parties involved. Union Berlin is expected to receive a similar transfer fee to what they initially paid for him.

Ivan Prtajin was initially considered as part of a deal to sign Ragnar Ache from Kaiserslautern. However, the deal did not materialize.

Kaiserslautern was one of several second division clubs interested in signing the Croatian striker after the end of last season. They might want the Croatian on at least a one-season loan, but this depends on whether Ache leaves Kaiserslautern.