Sunderland will be without Lamine Kone for at least a month.
Ivory Coast boss Marc Wilmots has revealed that the Black Cats centre-back has a problem with his knee and adductor muscle, which is expected to keep him out for a period of four to six weeks.
It means he could miss the majority of Sunderland's schedule for the rest of 2017, with the Black Cats playing nine championship games before the turn of the year.
Sunderland are hopeful that promising centre-back Tyias Browning will be fit to return from a hamstring injury after the international break, with John O'Shea and Marc Wilson paired at the heart of defence in the last two games.
Sunderland do have a number of emergency options in that position should they suffer further injuries, with Brendan Galloway, Paddy McNair and youngster Thomas Beadling all capable of stepping in.
Jack Rodwell has also recently played in that position for the U23 side as he looks to relaunch his career.
Club captain O'Shea picked up a calf problem during the 1-0 defeat to Middlesbrough but has since joined up with the Republic of Ireland squad and played a full part in training.