DArcy limped off in the first half of his sides opening championship fixture against Italy and despite a spell in a specialist rehabilitation centre in Spala, Poland, he has not figured in Irelands Grand Slam bid since.

A run-out for Leinster on the weekend confirmed the 25-year-old is not yet ready to make his Test match return and he has been ruled out of Saturdays mouth-watering clash with France at Lansdowne Road.

But OSullivans assessment that DArcy might not be fit for the potential Grand Slam decider against Wales on March 19 is a more significant blow, given he is rapidly running out of time to push his claims for British & Irish Lions selection.

Im worried about Gordons availability for the Wales match because his recovery has slowed down so dramatically. The situation is a concern, said OSullivan.

We were confident last week that he would be fit for France and we thought he would be fine once he got onto the pitch for Leinster. But he didnt have as much power as he wanted and at that juncture we knew he wasnt right.

He had some discomfort in his hamstring and underwent a scan (on Monday) which revealed some residual scarring that hasnt cleared up. Thats the reason he hasnt got full power.

Hes 95 per cent there but that last five per cent is taking a lot longer to heal than expected.

He hasnt improved much over the last week. He can run but not at full speed. Its a Test match so its not as if we can throw him in and see what happens.