Ulster will have to wait until later in the week to discover if flanker Marcell Coetzee will be available for their trip to Leinster on Saturday.
The former Springbok sustained a concussion in last week's 21-12 loss to Connacht in Galway and will now undergo the return to play protocols.
His absence would be a big blow for Ulster should he miss the trip to Leinster, with the South African in excellent form to start the season after returning from long-term injury.
Loosehead prop Tommy O'Hagan will definitely miss the tie at the RDS Arena in Dublin after he picked up an ankle injury at the Sportsground.
The Rainey club man, who made his senior debut last week, will go for further investigation to determine how significant the injury is.
However, there is good news for Dan McFarland and his coaching staff with Wiehahn Herbst (groin), Alan O'Connor (ankle) and Andy Warwick (knee) all available for selection again.
Warwick should slot back into the loosehead rotation with the impressive Eric O'Sullivan, while O'Connor will provide significant relief to an injury-ravaged second row.
Herbst, meanwhile, will return to fight for a spot on the tighthead of the scrum along with Marty Moore, Tom O'Toole and Ross Kane.