Mame Biram Diouf has reported back to training after missing a number of sessions with Hannover.
Diouf has yet to complete a full training session under new coach Tayfun Korkut, and the club have been left far from happy with the Senegal striker's behaviour.
Dirk Dufner, the Hannover general manager, said: "We definitely do not like this (the player staying away from regular training).
"This is not anything we have agreed with him."
Diouf is out of contract at the end of the season and has so far refused Hannover's attempts to discuss a fresh deal.
Stoke City have been tracking him since last January - but Cardiff City, now managed by Ole Gunnar Solskjaer who had Diouf at Molde, are also said to be keen.