Sunderland will be without Duncan Watmore, Jeremain Lens and Younes Kaboul for the visit of Manchester United on 13 February. Lens, 28, was forced off during the 1-0 defeat to Manchester City on 2 February, missing the 2-2 draw with Liverpool four days later as a result.
Speaking at a press conference ahead of the visit of Louis van Gaal's side, Sam Allardyce revealed the Dutchman is suffering from a suspected hernia, as confirmed via Sunderland's official website.
Watmore, meanwhile, was forced off during that draw at Anfield after an awkward landing left him unable to continue. The England Under-21 international has suffered suspected ankle ligament damage, a potential blow to the Black Cats hopes of remaining in the Premier League with Lens also facing a lengthy spell on the sidelines.
Kaboul is also an injury absentee after suffering an ankle problem of his own earlier in February. The French defender was set to return and make his first appearance for the club since December 2015 at Anfield, only to suffer another setback that is expected to rule him out until the club's visit to West Ham United at the end of the month.
"Younes Kaboul suffered a fresh injury – ankle ligament – in training the day before the Liverpool game and Duncan Watmore is going to be considerable time with ankle ligaments as well," Allardyce told reporters. "Younes hasn't done it too badly but Dunc has a bit more of a problem due to the rotation in the ankle when he hit the floor, so we will have to see how it responds in the next 10 days to two weeks.
Sebastian Larsson also remains sidelined with a medial ligament problem. "Seb Larsson has joined in training but he won't be put in the squad because it's too early this weekend," the manager said. "We have one or two other niggles; Billy Jones has a hip problem and after that it's just bumps and bruises, but certainly Duncan and Younes are out of the picture for this weekend."
Allardyce has also confirmed Adam Johnson will not be available for the match amid his ongoing court case.