Simon Grayson is 'hopeful' a deal for goalkeeper Robbin Ruiter can be concluded.
Ruiter was not part of the matchday squad that lost 5-0 to Celtic but the Black Cats boss insisted that was expected.
There is reported interested in the 30-year-old from Burnley and Hull City.
Jason Steele struggled on his debut and Grayson said last week that he wanted to replace both Jordan Pickford and Vito Mannone.
He said: "He was always going back to Holland, he had some issues to sort over there but we’re talking to his agent and we’re hopeful might be able to complete a deal."
Grayson also admitted that Jeremain Lens could soon leave the club.
The Black Cats rejected a bid from Besiktas late this week as they felt it did not meet their valutation.
The Dutchman signed from Dynamo Kyiv for £8 million and retrieving a good chunk of that fee will be crucial if Grayson is to reinvest in his squad.
He said: "Obviously everybody is aware that we had a bid which we didn’t think matched his valuation but he was injured from the Bradford game and so he wasn’t available. It depends how he goes in the next few days, he might not be here in a few days if a bid comes in.
"We’ll have to wait and see [if he's fit for Derby], we’ll analyse him tomorrow morning and take it from there."
Grayson added that it was too soon to tell if the likes of Wahbi Khazri and Josh Maja would be fit for the season opener. Khazri was substituted after picking up a knock in the first half.