Dortmund's "Borussia" revealed that Kuba Blaszczykowski, a winger struggling to recover from a string of injuries, will miss the team's tour in Asia.
Last season, the Polish player only played 20 matches in all competitions, starting in just nine of them.
Missing out on a crucial preparation stage could make it difficult for Kuba to regain his form. The Bundesliga championship will start in just over a month.
The 29-year-old footballer moved from "Wisla" in Krakow to BvB in 2007.