The 47-year-old stepped down from his position as Dragons manager on Friday evening after declaring his interest in the vacant Stadium of Light position.
Coleman has all but confirmed that an agreement has been struck, however, with the midweek trip to Villa Park now expected to be his first game at the helm.
"I've got an early flight tomorrow and then up and straight into it," the Sunderland Echo quotes him as saying. "Then it is a big game on Tuesday night against Aston Villa at Villa Park."
Asked who he would like to replace him as Wales manager, Coleman added: "It needs to be a passionate Welshman, for me. But I obviously don't make that decision, that will be the powers that be. But it needs to be another Welshman, for sure."
Kit Symons, formerly Coleman's assistant in the Wales coaching setup, was present at the Stadium of Light as the Black Cats' home woes continued.