KEIL O’Brien will be out for at least three weeks after the centre-back picked up a knee injury on his promising debut at Luton last week.

Shakers manager David Flitcroft revealed the 22-year-old summer signing from Chorley “tweaked” the medial ligament of the same knee he injured in pre-season training.

That injury kept O’Brien out for four months and there were fears he could be facing an even longer stay on the sidelines after being clattered in the first half of Bury’s 1-0 FA Cup defeat at Kenilworth Road.

But while the talented young defender will have to endure another frustrating spell on the sidelines, Flitcroft says scans revealed no long-term damage.

“He got a tackle on about 35 minutes and it was a meaty one, right underneath us and we feared the worst,” said the Bury manager.

“Luckily, it could be about three weeks. He has just tweaked his medial. We were expecting worse. You should have seen how it ballooned.

“It was the same knee (as his previous injury) but it was not a recurrence of that."

Positive news from O'Brien's scans on his injured knee will be cold comfort for player and manager, however, after months of hard work to help manage the leap from the Evo-Stik Premier Division to league football.

“I am disappointed because the reason we brought him here was to develop him and get him into the first team and he looked composed and calm in what was his first opportunity," added Flitcroft.

“There is some untapped potential in that boy. A little bit gutted that he has not been able to get a little rhythm going because he would have probably started (against York).

“But we will get him back, and luckily we are not talking about something that’s long term here.

“He’s quite positive because we thought it might have been a six-monther.”

Flitcroft is likely to have just three centre-backs available for selection on Friday and possibly throughout the festive period after confirming that Pablo Mills had aggravated a groin injury in Saturday’s draw against York.

The former Derby defender underwent a course of injections to play at the weekend, but suffered a recurrence near the end of the first half and was replaced at the break.

“Pablo had some injections and we thought it had really settled down,” said Flitcroft. “If he over-stretches it just causes a flare-up in his groin and stomach area, so we might have to now maybe leave him out a touch longer to really get right.”

There was further bad news for the Bury manager on Saturday after it was confirmed that loan defender Rob Milsom had returned to parent club Rotherham after tearing a thigh muscle in the recent defeat at Oxford.