World Cup victor Mario Gotze has been ruled out for the rest of the season as he recovers from a "metabolic disorder" but is expected to be "fully fit" for the start of next term.
The Dortmund website said: "good news for Mario Goetze: Borussia Dortmund's Germany global speaks positively about the first phase of his treatment", but included no direct quotes.
Gotze has been placed on an individual rehabilitation programme and the club are hopeful the world cup victor can get back to full training in the summer if treatment goes to plan.
The club had pulled Götze out of training on February 27, shortly after his "metabolic disturbances" were diagnosed.
However, poor form and injury meant he has played just six games over the 90 minutes this season and he has been a shadow of the player which left Dortmund in 2013.
The long term target for the player is to be fully fit and ready to play for the start of next season. The player is now undergoing rehab and an individual training programme.
Last month Dortmund confirmed the 24-year-old's recent spate of muscular problems had been caused by the "metabolic" issues, and ruled him out for an undetermined period of time.
Dortmund CEO Hans-Joachim Watzke added: "BVB wishes Mario Gotze a quick recovery on behalf of his ten million fans".