Chancel Mbemba could be sidelined for more than a month at injury-hit Newcastle United.
Head coach Steve McClaren has a defensive crisis on his hands ahead of tomorrow's home game against West Bromwich Albion.
Mbemba aggravated an ankle problem in Wednesday night's 3-0 defeat to Everton.
McClaren said: "By next week we'll know the full diagnosis."
Paul Dummett suffered a recurrence of a hamstring problem in the same game, while a third defender, Jamaal Lascelles, is suspended after his late dismissal at Goodison Park.
On Dummett, McClaren said: "It's a little niggle. He felt a tightness and we didn't want to take a risk. He's not fit for tomorrow."
Midfielder Jack Colback – able to play at left-back – remains sidelined with a hamstring injury.
McClaren added: "Jack's very, very close."