Fortuna Dusseldorf are sending Zak Steffen back to Manchester City.
Steffen will return to City for tests on a persistent knee problem he has been suffering at Fortuna Dusseldorf.
Steffen has not played in five games in 2020, but has 18 appearances all season.
A Fortuna statement said: "Goalkeeper Zack Steffen will undergo medical examinations over the next few days due to his persistent knee problems, which are organized by his home club Manchester City.
"Fortuna's physiotherapist Lucas Trittel, who is involved in all processes as part of the medical department, will accompany Steffen to act as a contact person.
"Both clubs are in constant communication: Fortuna's sports director Lutz Pfannenstiel and Manchester's sports director Txiki Begiristain have agreed on this procedure in close consultation with the medical departments of both clubs."