Steve Bruce says that Ciaran Clark's season ending injury is a huge blow to his squad after the Irish defender had proved to be one of the players of the campaign so far.
The former Aston Villa man picked up an ankle injury in the 4-0 defeat at Arsenal and United are now deciding whether he goes under the knife for an operation or not.
When asked about Clark, Bruce said: "I think he's been excellent.
"It's been cruel for us, Matt Ritchie after a tackle, now Ciaran and Dummy before him.
"When that happens you can't legislate for it. It's bad news for all of us.
"Even with Dummy and Ciaran out we still have four, in that area we are quite strong."
Bruce has Federico Fernandez, Jamaal Lascelles, Florian Lejeune and Fabian Schar vying for places in his back five.
He also received a boost with Javier Manquillo and Jonjo Shelvey back in training.
However, the Burnley clash comes too early for Andy Carroll, still out with hamstring and hip problems.
Bruce said: "Andy has not trained but the rest are OK.
"Jonjo has trained, Manquillo is back and all of a sudden we have 20 or so outfield players out there.
"You can only pick 11 and the other 10 will be disappointed.
"Most of the players understand that without a squad you won't survive.
"I expect half-a-dozen players won't be happy."
