Black Cats boss steve Bruce is keen on the Paraguay international and will reportedly throw in a £4.2million bid to get the 26-year old for a bargain basement price.
Valdez says he is open to a move but admits there is plenty of competition for Sunderland.
"There is a lucrative offer from the Netherlands (PSV Eindhoven) I have received. But there is also interest from Russia, Portugal and England. My agent is weighing up options," Valdez said.