Wolves' Bakary Sako has revealed he is mulling over offers from the Premier League but is yet to decide on his future.
Rotherham boss Steve Evans will decide the fate of his out-of-contract players in a meeting on Monday.
The 32-year-old defender spent two years with the Spanish outfit, but saw out the latter part of last season on loan at Russian club Anzhi Makhachkala.
It was the Bosnian international's third spell in Russia, having previously played for Torpedo Moscow and Lokomotiv Moscow.
Bayer, third in last season's Bundesliga, have moved swiftly to add Spahic to their ranks.