Rob Herring has flown to Japan to replace the injured Sean Cronin in Ireland's World Cup squad.
Leinster hooker Cronin has suffered a neck injury and has been ruled out of the rest of the tournament.
Ulster front-rower Herring has linked up with Ireland, who face New Zealand in Saturday's quarter-final in Tokyo.
Ireland have also confirmed they will not appeal the three-week ban handed out to centre Bundee Aki, for his red card against Samoa.
"Sean aggravated a pre-existing neck muscle complaint and has been ruled out of the remainder of RWC19," read an Irish Rugby Football Union statement.
"Rob Herring has joined the Ireland squad in Tokyo.
"The Ireland Management will not appeal the sanction handed down to Bundee.
"We are disappointed with the outcome and believe that Bundee's time will be best served helping prepare the squad for its remaining RWC19 fixtures."
