George Honeyman has been ruled out of the Swansea City game with a back injury - after Lamine Kone fell on top of him in training.
The training ground mishap will see the Academy product miss tomorrow's game against relegation-threatened Swans at the Stadium of Light (KO 3pm).
Honeyman started the 2-0 win over Hull City and is one appearance shy of triggering an automatic contract extension, although manager David Moyes has already said he is keen to retain his services next season.
Speaking at his pre-match press conference, Moyes said: "George has got a back injury. He picked it up in training when Lamine Kone fell on top of him.
"I'm trying to introduce some younger players; George's performance merited another start so I'm disappointed he won't be available."
The Sunderland boss last week gave a strong indication he would remain at the helm next season despite the club's relegation from the Premier League.
Further talks about how Sunderland bounce back are planned with owner Ellis Short and chief executive Martin Bain for the end of the season and Moyes was again asked about the future at his press conference.
The Scot said: "I have a four-year contract and we're all working hard behind the scenes to get things right from pre-season to players - I hope that we're able to build a team that can get us straight back up."
The Black Cats go into the game on the back of the 2-0 win over Hull, Moyes added: "We were pleased with the result and the performance.
"Now we have another game and we want to win and finish the season strongly. We're not over relegation but we're trying to put it behind us and win as many games as we can heading into the new season.
"We are a greatly supported club whether it be home or away. We have a great fan base and we want to end the season well.
"It was great for Jermain Defoe to get a goal last week. We've needed his goals all year and everyone at the club hopes he stays."
The 15-goal top scorer can leave on a free in the summer in the wake of relegation and the Swansea City game is set to be his final game for Sunderland at the Stadium of Light, with a host of Premier League clubs keen to sign him.
There was a fitness boost elsewhere, though, with midfielders Lee Cattermole and Darron Gibson returning to training this week along with left-back Bryan Oviedo who has been out with a hamstring injury.