Ireland's preparations for the upcoming Tests were dealt a double blow when captain Brian O'Driscoll and hooker Rory Best were both ruled out of the series.
O'Driscoll must undergo surgery after injuring his ankle while playing for Leinster against Cardiff Blues last Saturday, while Ulster forward Best sprained neck ligaments in a match against the Newport-Gwent Dragons on Friday.
Ireland face South Africa, Fiji and Argentina in the internationals, and the absence of the inspirational O'Driscoll is likely to have a serious impact on their ambitions.
The 33-year-old centre is in the last year of his contract with the Irish Rugby Football Union and his future beyond next year is yet to be decided.
His unavailability presents Ireland coach Declan Kidney with further problems in his back line, as fullback Rob Kearney has already been obliged to withdraw from the squad due to injury.
With O'Driscoll out, the captaincy is likely to be handed to Lions skipper Paul O'Connell.