Ireland’s Iain Henderson and Jacob Stockdale will miss Ulster’s New Year’s Day Guinness PRO14 Irish derby with Munster.
It had already been planned that both would miss the crunch Belfast clash, Director of Rugby, Les Kiss confirmed on Thursday.
Both had played in last Saturday’s visit to Galway when Ulster suffered a 44-16 mauling.
Ulster had made nine changes to their line-up, plus moving winger Stockdale to fullback, for the game at The Sportsground.
All four Provinces usually have squad rotation around this time of the year during the Irish derby games.
Kiss admitted they had already planned to rest the Irish duo who had featured prominently during the November Guinness Test series in the green jersey.
“It is trying to judge it all. We rested a few last week and then the sickness got us, it then threw things out a bit, but you have to deal with that.
“Ultimately we try to get the rest periods right. It probably hit us a little bit last week, we still had four or five who could not train today due to a viral going around and through the place at the moment.
“A few of us are feeling it, but we have to just get back on the horse and get on with it,” he said.
Ulster’s front row came under pressure against Connacht and they had hoped to have props Kyle McCall and Rodney Ah You back in the mix for the game against Munster.
However, the pair collided during training on Thursday and needed stitches to respective head wounds - leaving speculation on if either would be involved.
Kiss remained hopeful both would be okay to feature. Both McCall and Ah You are making their return from injury.
Ulster will also be without Sean Reidy and Chris Henry in the backrow having picked up knocks, but there was some good news from Kiss when he confirmed South African Jean Deysel was back in the mix for selection this week following injury.
Hopes that centre Luke Marshall would be back in time for the Munster game were dashed further.
Kiss said: “He has an achilles issue and it is still taking its time.
“He has started running and hopefully two weeks gets him back into a closer picture in terms of being available for us in the centres.”
Tommy Bowe and John Andrew both remain unavailable along with the other long terms injuries which include captain, Rory Best, Marcell Coetzee and Jared Payne.
Along with Deysel, hooker Rob Herring looks set to start on Monday as he has recovered from injury, while Stuart McCloskey is also available.
Outhalf Christian Leali’ifano also returns to the side.
Kieran Treadwell was expected to be back although Ulster were monitoring him after he turned on an ankle during training yesterday.
Meanwhile, Keith Earls has recovered from the illness which ruled him out of Munster’s inter-pro defeat to Leinster.
The Ireland international had been originally named to start against Leinster after shaking off a hamstring injury which had kept him sidelined since the start of November, but was a late withdrawal after falling ill over the weekend.
Munster have reported a relatively clean bill of health from the 34-24 loss to Leinster with James Cronin coming through his return from a calf injury unscathed while Ronan O’Mahony and Conor Oliver today returned to full training.
However, hooker Rhys Marshall continues to be monitored following a concussion against Leicester Tigers in the European Champions Cup.