Iain Henderson is out of Ireland's Six Nations clash with Italy after producing a Covid result.
The Ulster skipper was believed to be in to return to the starting line-up as James Ryan's second row partner at the Aviva Stadium on Sunday.
He came off the bench in the championship defeat in Paris a week and a half ago but had failed to displace in-form Tadhg Beirne in the side.
However the Covid result came from routine testing of squad and management upon arrival into Ireland camp on Monday evening.
"Iain is well and has left Ireland camp to complete his period of isolation at home," read an IRFU statement.
"There are no other positive results within the group and the squad will continue to test across the week."
Henderson is the second Ulster player to withdraw from the squad this week.
Prop Tom O'Toole was ruled out on Tuesday as a result of the hamstring injury he suffered while in action for the province against the Dragons last Sunday.
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