The centre underwent ankle surgery in June and with a projected six-week recovery time, the 31-year-old looks certain to miss Ireland's World Cup warm-up games - with the first against Scotland on August 6.
The 57-cap centre picked up the injury in Leinster's epic Heineken Cup final win over Northampton and D'Arcy originally hoped for the injury to heal itself naturally. This soon proved to be a forlorn hope and the Wexford-born centre went under the knife on June 20.
And Kidney has now conceded that D'Arcy faces a race against time to make the plane to New Zealand. "Unfortunately Gordon's ankle didn't solve itself so he needed an operation and it will take a good six weeks to be running fully, then you need a pre-season, which is another couple of weeks, so it's getting tight," Kidney said.
Ireland start their World Cup preparations against Scotland on Saturday before facing France (twice) and completing their schedule against England on August 27.
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