Second row blow for Ireland
Ireland will have to make do without veteran lock Paul O'Connell when they take on South Africa in Dublin on Saturday.
O'Connell returned to training at the start of the week and took a full part in the squad sessions at Carton House on Monday and Tuesday.
However, the Munster lock suffered a reaction to a recurring back injury and will not be fit for selection for this weekend's game against the Springboks.
"Paul will see a specialist in the coming days and an update will be issued in due course," the Irish Rugby Football Union said in a statement.
The absence of O'Connell for the opening match of Ireland's November campaign came after Brian O'Driscoll, Sean O'Brien, Rob Kearney and Rory Best had all been ruled out of the whole series, which includes next week's non-cap match with Fiji and a Test against Argentina on November 24.
Meanwhile back row forward Stephen Ferris is, at best, expected to feature only in the Argentina match because of an ankle injury.
As well as needing to find a new lock in the absence of O'Connell, the British and Irish Lions captain on the 2009 tour of South Africa, Ireland coach Declan Kidney must now also find a new skipper given O'Driscoll and Best are sidelined as well.
Kidney is due to name his side to play South Africa on Thursday, with the captaincy set to go to either No.8 Jamie Heaslip or flyhalf Jonathan Sexton.
* With the 2015 World Cup pool allocation draw set to take place on December 3, tighthead prop Mike Ross said the Irish are well aware of how much is riding on Saturday's result, with the men in green also keen to improve their record at the Aviva Stadium.
Declan Kidney's men lie seventh currently in the world rankings list, thus making them second seeds. If their results in the year-end games against South Africa and eighth-ranked Argentina cause them to fall to ninth, they would enter the third tier and get a tougher pool draw in the process.
"You certainly don't want to end up in a pool with two other heavyweights. It makes it that much tougher to qualify for a World Cup quarterfinal," said Ross.
"It is very important that we do well in this series, especially against Argentina who are just a couple of ranking points ahead of us. We don't want to slip down, we want to do well.
"We have a home record at the Aviva to look at as well. It hasn't been where it's needed to be in the last couple of seasons. It's a big challenge for us to step up to improve that."
Ireland's home run is heading in the right direction - they beat Italy and Scotland in their last two outings in Dublin during the Six Nations.
They will also draw confidence from their 15-10 defeat of the Springboks at Croke Park in November 2009, a tight encounter swung by Jonathan Sexton's haul of five penalties.
Sexton and company come into the new campaign determined to banish memories of their 60-0 loss to New Zealand from four-and-a-half months ago.
Anthony Foley, who is overseeing Ireland's defensive plans during the November internationals, admitted: "The guys who played in that Test match [in Hamilton] will have that ringing in the back of their heads every night they go to bed - because it's a horrible place to be.
"It's not the first time it's happened. I've been involved in a few nightmares [as a player] as well.
"What you look for the next time out is making sure you can right that wrong. And it's a massive opportunity for that 23 who go out to put that to bed and not so much forget about it, but make it a driving force for you through the game and through the campaign."
Recently arrived New Zealander Michael Bent could be named on the bench despite having not yet played for Leinster since he touched down on Irish soil last week.
Asked about the newcomer, who will challenge for his No.3 shirt at Leinster and Ireland, Ross said: "If he is doing well against the top two or three looseheads in Ireland, you have to think he will be well able for the international stage.
"There are other Irish players who have played for Ireland without playing for an Irish province. You look at Kevin Maggs who was playing for Bristol and Geordan Murphy spent most of his time at Leicester.
"The fact is he is probably one of the guys out there who is match fit at the moment and has a good season at Taranaki.
"I think he has every right to be here and if he plays well nobody will be saying a word about him."
The Ireland team will be named on Thursday.