Borrussia Dortmund coach Thomas Tuchel denied the rumours of a possible move of Ginter.
The 22-year-old joined the yellow club in 2014 from Freiburg and is viewed as their new Mats Hummels.
Ginter didn't participate on the China pre-season tour due to an infection.
The coach explained in a press conference:
"With Ginter, I think everything is said. German clubs wanted to sign him and now English clubs want to sign him.
"I don't know if everything is true or it is just rumours but we made our point clear - Matthias is our player and stays our player.
"I am not disappointed that Nevan comes back. I am disappointed because it was his wish to get the transfer and to play in England and to play for Middlesbrough so I am sorry for him.
"For me he is welcome, he is our player still. He has a contract.
"He needs to have surgery. That is latest information I have so he will get all our support to come back strong. He will get all the support every player gets who is with our squad".