Andrew Trimble will undergo a scan tomorrow to try and establish how badly serious his foot injury is.
The Ulster winger picked up the injury in Saturday's win over Wales and is now waiting for a medical update on the length of his lay-off.
Trimble is coming off the back of an injury affected season, which saw him spend a spell on the sidelines because of a toe injury.
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Meanwhile, Marty Moore and Luke Fitzgerald have both returned to full contact training, while Cian Healy is progressing well in his recovery from his neck injury.