Irish provinces Leinster and Munster have joined the English clubs in making their players unavailable to play for the Barbarians against World Cup winners South Africa.
The Springboks conclude a short tour with a clash against the Baa-Baas on December 1 but the clubs are unwilling to release players due to other commitments.
The decision means Ireland centre Brian O'Driscoll will not captain the invitational side as had been planned.
A joint statement from the provinces read: "Contrary to media reports, neither Brian O'Driscoll nor Paul O'Connell nor any of the selected squads from the Leinster or Munster panels will be available for the upcoming Barbarians match against South Africa."
As head coach Stuart Lancaster polishes the axe he will soon wield over his World Cup training squad, Exeter Chiefs coach Rob Baxter has backed Jack Nowell, Henry Slade and Luke Cowan-Dickie to be given a stay of execution.
Italy Under-20s held off a late Samoa blitz to retain their place in the World Rugby U20 Championship on Saturday and head coach Alessandro Troncon believes the experience will have served as a valuable lesson for his young troops.