The optimistic prognosis over O’Connell’s back injury was confounded yesterday when the 2009 Lions skipper’s recovery was hit by a complication, forcing him out of the Springbok Test.

“Paul returned to training at the start of this week and took a full part in the squad sessions on Monday and Tuesday,” read a statement released by the Irish Rugby Football Union.

“However, he suffered a reaction and will not be fit for selection for this weekend’s game.

“Paul will see a specialist in the coming days and an update will be issued in due course.”

O’Connell is traditionally the automatic choice to lead the team in O’Driscoll’s absence but with one eye on the future Kidney must now opt for Jamie Heaslip or Jonathan Sexton instead.

The composition of the back row will be of interest in the absence of Ferris and O’Brien – two of Europe’s most destructive players – with Peter O’Mahony and Kevin McLaughlin likely to join Heaslip.

Simon Zebo and Denis Hurley are competing for the full-back duties with Keith Earls replacing O’Driscoll at outside centre.

Ireland have lost their last four Tests, the most of recent of which was their 60-0 mauling by New Zealand in June.

With IRB ranking points critical to seeding for the next World Cup at stake, it is imperative they dispatch opposition that is also missing several big names.

South Africa remain heavy favourites for Saturday, but scrum-half Eoin Reddan insists Ireland have a point to prove.

“In reality, the reason to win it on paper is the World Cup rankings,” Reddan said.

“But for the country, the fans, the players themselves and the coaching staff, it would be a huge opportunity to put the summer tour behind us.

“Even if this was a Six Nations game and we won, I don’t think we’d be putting New Zealand to bed.

“The fact that it’s a southern hemisphere team brings it closer to home that if we do beat them it’ll be a big step forward in the right direction.”