The 28-year-old Gabonese star who scored 31 goals in the German top flight last season has been in contact with several clubs, including Paris SG, AC Milan and Tianjin Quanjian from China.
To date no club has secured his signature and the former African Ballon d’Or winner remains under contract with Dortmund.
And he was among players put through their paces Friday by the Ruhr club, undergoing physical tests before the official resumption of training.
On Tuesday Dortmund will play their first friendly of the season against German fourth-tier club Rot-Weiss Essen, the first match in charge for the club’s new Dutch coach Peter Bosz, who signed from Ajax Amsterdam.
The German club will participate in the Champions League again this season after finishing third in last season’s Bundesliga.
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