Sunderland have been quite busy in the summer transfer window.
Donald has also suggested that the Black Cats could even add three more players in total in the summer transfer window.
The League One club have been quite busy this summer and have made a number of signings already.
Sunderland have secured the services of Conor McLaughlin, Ahmed Abdelkader, Lee Burge, Ruben Sammut, Michael Collins, Jordan Willis, George Dobson and Marc McNulty (loan) already this summer.
Donald told Roker Report: “We’re talking about strengthening the team with two or three more signings before the window shuts.
“A couple of players on the desk are probably going to cost us half a million pounds if we decide they are the ones to go for.”
The Sunderland owner added: “We’re not far away on one and that one may extend to three but it might end up being two.
“If you asked me now, I would hope we will sign a couple of players next week but I would certainly expect there to be one. They’re defensive players.”
Promotion challenge
Sunderland have a strong squad, but Jack Ross’s side have not made a great start to the season.
The main reason why the Black Cats could not finish in the top two of the League One table last season was too many draws, and things have not changed so far this campaign.
Sunderland have drawn two and won one of their three League One games so far this season.
The Black Cats are back in action on Tuesday evening when they take on Rochdale away from home in League One.
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