The 30-year-old is his country's biggest injury concern ahead of the final round of the Six Nations but he has not been ruled out of Saturday's encounter.
D'Arcy limped off during the first half of Ireland's comfortable win over Wales at the weekend.
He suffered deep bruising above his left knee and is currently being closely monitored by the Irish medical team.
D'Arcy will miss today's light session and will continue to be assessed throughout the week.
Double tryscorer Keith Earls is a slight worry after complaining of tight calves but the Munsterman is expected to be available for the Croke Park clash.
Munster team-mate David Wallace is in a similar situation having received an accidental scratch to the eye during the 27-12 triumph over Wales.
Like Earls, he will be monitored during the week but is likely to be fit when Ireland go in search of another Triple Crown success against a winless Scotland.
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