Ulster must factor without both Iain Henderson and Stuart McCloskey for the next few weeks.
The province confirmed on Tuesday that Henderson suffered an ankle injury in last Friday's Heineken Champions Cup win over Northampton.
McCloskey also came a-cropper in that game at Kingspan Stadium, sustaining a hamstring problem.
Both will be in a race to be fit for the start of Ireland's Six Nations campaign, which is already just six-weeks away.
In better news for Ulster, Tom O'Toole, Matty Rea and James Hume have signed new two-year deals. All three will stay in Belfast until the summer of 2024.
Tighthead O'Toole made his Ireland debut in the summer's Test victory over the USA at the Aviva.
Now 28, Rea has established himself as one of the province's go-to flankers, while also able to offer a hand in the second row.
23-year old Hume could make his 50th Ulster appearance in their St. Stephen's Day meeting with Connacht.
"He’s playing very well," Ulster defence coach Jared Payne said of Hume this week, "He’s put in a lot of work off the pitch on all aspects of his game.
"He’s matured a lot in the last year-and-a-half and worked very hard to get to where he is. So it’s good to see him getting the reward."
Greeting the trio's new deals, head coach Dan McFarland said, "All three add a huge amount to the squad, with Matty demonstrating his value as a lineout operating and ball carrying 6.
"Tom is still a young tighthead but has already earned international recognition for his relentless workrate and physicality.
"James has made a big breakthrough this year, adding consistency in his fundamentals to a top-class ability to beat defenders.
“I look forward to seeing what the next two years hold for this group of young players."
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