The 18-year-old appeared to slip and twist his leg awkwardly in the 1-0 defeat at Old Trafford.
“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.”
