The 22-year-old has not been able to settle in at his new club since a reported ?10.5million move from German giants Hamburger SV in 2010.
However, the German international may find it difficult to complete his dream move back to the Bundesliga because Roberto Mancini seems to be taking a stubborn stance on his ?17million valuation.
That transfer hike has angered Rummenigge in particular who believed City were using "tactics" to get clubs to stump up extra cash unfairly to capture the versatile defender's services.
"They are using a tactic I've never seen. They don't respond, even if we try to contact them," he told The Sun.
"I think they are going to have 48 players under contract but, according to Financial Fair Play, they can have only 25.
"According to their last balance sheet, if I'm correct, they're down ?127million.
"Maybe they still have a trick up their sleeves but I'm not sure they will be permitted to play in the Champions League."
Source: Team Talk
Source: Team Talk