It has been reported that Mainz chief Christian Heidel is prepared to sell Yoshinori Muto this month.
Manchester United have been linked with the striker and Rhein-Main-Presse says Heidel is willing to sell for the right price.
Muto arrived at Mainz for €2.8 million from FC Tokyo and Mainz expect a bid from United to arrive in the region of €16 million.
Mainz coach Martin Schmidt is reluctant to lose Muto, but understands anything can happen this month.
“Sometimes just before the market closes, all sorts of deals happen,” says Schmidt. “Everything blows up.
“It can happen to anyone.”