Sunderland have approached Schalke for Dennis Aogo.

Black Cats boss David Moyes is keen to strengthen his defensive options before the market shuts this month.

Sunderland have asked Schalke about Aogo's availability, along with Villarreal, says Reviersport.

For the moment, however, Schalke insist Aogo is not for sale.

"As it stands now, no more players will be leaving us," stated S04 chief Christian Heidel on Thursday.