Sunderland boss Steve Bruce fears Connor Wickham suffered a serious knee injury in the 1-0 defeat at Manchester United.
The 18-year-old striker appeared to slip and twist his leg awkwardly, leaving Bruce to contemplate the loss of another player to ligament damage.
Wickham is the latest Sunderland player to suffer such a setback along with Fraizer Campbell (twice), Titus Bramble, Michael Turner, Craig Gordon and David Meyler.
"That's the big disappointment of the afternoon for us because we think it's a serious knee injury, and that's now seven we've had in 12 months," said Bruce.
"We hope it's not what we think it is but the signs don't look good.
"It's unbelievable. I've never known anything like it."