Simon Grayson admits he is still searching for his best defence after the Black Cats shipped three goals at Griffin Park.
Injuries and poor form have forced the Sunderland boss to change his defence regularly, with his side now holding the joint-worst record in the division alongside Burton Albion.
Grayson hopes to be able to call upon injured duo Marc Wilson and Tyias Browning soon and says building towards clean sheets will be his main priority on the training ground.
He said: “Marc’s trained this morning so he’ll get a week’s training and hopefully come through it to maybe be available for the weekend.
“Tyias had a little setback on Thursday with his hamstring, so we’ll see where he’s going to be for the next couple of games.
“A few weeks ago we weren’t scoring and people said that was the issue, now we’re scoring and it is about us conceding. It is about getting the balance right, of course it is, it is getting partnerships and understanding and consistency in selection.
“I don’t think there were many individual mistakes for the goals, we know we need to work hard on it on the training pitch because we’ve got the players to win us games if we keep clean sheets.
“Every manager and any supporters as well will tell you that when there’s a consistent team selection the opportunity to keep clean sheets is easier because there’s more understanding of partnerships and cohesion within the group. Do I know my strongest back four? Not really because we’ve not been able to put everybody together at one particular time.”
Grayson will consider making further changes for the crunch tie with Bristol City this weekend, admitting that not many of his players had performed to a level that nails down a regular spot.
Grayson said: “I agree totally and that’s sometimes why you do chop and change. A manager leaves you out, really, if you’re not playing well enough to contribute to the team.
“Players have to give me a major problem by playing so well that I can’t leave them out, whether that’s an attacker, goalkeeper, defender or midfield player.”
Grayson will also be monitoring the fitness of Jonny Williams, still a doubt with a hamstring niggle, and Callum McManaman, who has a dead leg but should return to training on Tuesday or Thursday.