Ulster may ask the IRFU to allow them to make an emergency signing as they await a worst-case scenario following an exploratory knee operation on South African flanker Marcell Coetzee.
The luckless Coetzee made his Ulster debut in February after recuperating from another long-term injury to the same knee and, although the province are hoping that there is merely cartilage damage, director of rugby Les Kiss is bracing himself for the worst.
"Marcell saw the surgeon yesterday and the swelling is down so he's going to have that surgery tomorrow," said the Kiwi yesterday.
"It's exploratory. The word from the surgeon is that we'll find out the true extent after that. There's cartilage damage.
"We just don't know if it's that which is restricting the movement or if it's something else. I can't be any clearer than that, but worst-case scenario it's the ACL.
"It will be six to nine months depending on the severity. I'm only guessing to tell you the truth but the best case would be it's just cartilage and it'll be five or six weeks.
"There's obviously some damage there. It's quite sore and he's in a brace. We've got to wait to get to that point where we have clarity."
Asked, when he does receive that clarity, whether or not he will seek permission to recruit another back-rower, Kiss straight-batted the response. "I've got a meeting to chat about those things and see where that goes," he said.
"Clive Ross has been an unsung hero. He just puts in good performances. Sean Reidy and Chris Henry have really combined well, but Marcell definitely gave it an edge and a balance.
"We've got Iain Henderson back who can play lock and back-row so we'll have to just work with those options. It's not ideal but that's what it is."
Out-half Paddy Jackson, unused in last Saturday's success against England, did not train yesterday but will be available for the trip to the Dragons as Ulster step up their play-off bid.
Henderson, the sole try-scorer in the England win, and Jared Payne will both be available but captain Rory Best will be rested.
"He's had a fairly rugged time," said Kiss. "Rory and I have messaged each other and I've spoken to Joe (Schmidt) on the phone and that's where we'll go.
"Rob Herring has really come back into it and Johnny Andrew has been unreal for us so they'll get another chance to go on Friday."
Craig Gilroy, Luke Marshall and Stuart Olding will also start in Wales.
Meanwhile, Allen Clarke will hook up with Ospreys next season as their new forwards coach, replacing the brother of the man who has effectively ended his coaching stint at the northern province.
Clarke will assume the position from Chris Gibbes, brother of incoming Ulster head coach and former Leinster assistant, Jono.
Chris Gibbes is returning home to New Zealand as the new head coach of Wellington Lions. Clarke, 49, won eight Test caps between 1995 and 1998, while he also played for Northampton and Ulster.
"I'm delighted to have this opportunity and really excited about the next challenge in my career," said the former Ireland international hooker and European Cup winner.
"Why the Ospreys? What's impressed me are the people. Many organisations will have values and I get the sense that the people at the Ospreys really do believe and live their values.
"That creates a good environment to work in, a culture that I'm looking forward to being part of.
"It's an ambitious organisation, with a great mix of experience and some real talent coming through, and I hope that I can add value, for all at the club."