Will Addison is almost certain to miss the November internationals as Ulster today confirmed he has undergone surgery following a leg fracture.
The Ireland full-back - who played only three games last season due to injury - was injured during Ulster's United Rugby Championship win over Emirates Lions and will now be sidelined for a number of weeks.
"Will’s got a fracture to his lower leg," head coach Dan McFarland, speaking ahead of their game with Connacht on Saturday, said.
"He had surgery yesterday at the Royal Victoria hospital to stabilise that fracture. The surgery went well and he's recuperating.
"It’s way too early to [set a return date]."
Utility back Addison, 29, has won five Ireland caps since making his debut in 2018.
The head coach was non-committal on Iain Henderson’s thumb injury.
"He's making his way back from his operation on his hand so, we’ll see how that progresses, he’s close," he said.
Asked if the second row could miss Ireland’s upcoming internationals, against Japan (6 November), New Zealand (13 November) and Argentina (21 November), he said: "We’ll just see how it goes."
Despite a lengthy injury list that had included 14 players, Ulster find themselves top of the table with four bonus-point wins from four games.
"There's always an opportunity with injuries," added McFarland.
"Opportunities for guys who would have probably played in this section of the season anyway, maybe played a bit more than they would have done, strung a few games together."
McFarland has also predicted a derby, which has been moved to the Aviva by Connacht, with "extra spice in the challenge".
"We’ve been forward and back over the last couple of seasons, they’ve beaten us as many times as we’ve beaten them," said the former Connacht player and coach.
"There have been some corkers of games.
"Do you remember what happened the last time we played Connacht at the Aviva, we were terrible," he said of the August 2020 Pro14 clash Ulster lost 26-20.
"I think I’d rather play them at the Sportsground. The last time we played them there we played really well."