Schalke are seeking a medical update from Chelsea regarding Ghana defender Abdul Rahman Baba.
The 23-year-old is expected to return to Gelsenkirchen for another loan spell ahead of the new season.
However, the German outfit are seeking the medical situation of the Ghanaian from the English champions.
Rahman suffered a career-threatening injury while on international duty with Ghana in January.
The former Asante Kotoko left-back has intensified his recovery from the knee injury and Schalke have now asked Chelsea for a medical update before making their next move.
The German outfit are prepared to wait further to re-sign the defender, who impressed during his first loan stint at the club.