Ireland have already lost David Wallace and Felix Jones for the showpiece tournament with injuries.
Now D'Arcy has postponed his flight for 48-hours after picking up a calf strain during training. It is hoped the delay will reduce the chance of swelling during the flight to New Zealand but the centre is now a doubt for the big kick-off against the USA on September 11.
"Gordon D'Arcy's departure to New Zealand has been delayed by 48 hours," read an IRFU statement.
"The Ireland centre picked up a calf strain at a recovery session this morning prior to the Ireland squad departure for New Zealand.
"The injury was scanned and to minimise the possibility of any swelling on the flight, it has been decided that it is more prudent to allow the strain time to recover before he joins up with the Ireland squad in Queenstown."
Cian Healy will also not travel until the weekend as he receives treatment on a damaged eye socket while Brian O'Driscoll, Sean O'Brien, Jerry Flannery and Jamie Heaslip all jet south carrying knocks picked up during the warm-up series.