Johnny Sexton suffered a "whiplash injury" to his neck and shoulder in Ireland's 10-9 RBS 6 Nations defeat to France, according to head coach Joe Schmidt.
Fly-half Sexton appeared dazed on leaving the Stade de France field after several questionable hits on Saturday, but now Ireland boss Schmidt has moved to downplay any concussion fears.
Sexton was stood down for 12 weeks in late 2014 owing to four concussions inside 12 months, and has had several further head-injury concerns since.
The 30-year-old continues to shrug off whatever hits come his way however, including neck trouble from a blow to the head in Ireland's 16-16 Six Nations draw with Wales two weeks ago.
"Johnny Sexton, with his neck and shoulder, it's more of a whiplash injury," said Schmidt.
"And he is certainly feeling a lot better, 48 hours post-game."
On Monday, French second row Yoann Maestri was issued with a citing commissioner warning for using his shoulder in a tackle which lifted Sexton off his feet in the 13th minute of Saturday's match, saying the tackle fell 'just short of' warranting a red card.
Ireland head coach Schmidt will certainly want Sexton fit to face England at Twickenham on Saturday, February 27, and will now allow the Leinster playmaker as much recovery time as possible.
Sexton was even a concussion doubt ahead of the Six Nations after a blow to the head in Leinster's 51-10 defeat to Wasps, only for Ireland later to confirm he had passed all subsequent Head Injury Assessments (HIAs).
While Ireland remain hopeful over Sexton's chances of facing England, centre Jared Payne's outlook appears problematic.
Ireland had revealed Payne played through a dead leg in Paris, staying on despite the blow knowing that Fergus McFadden had already replaced injured wing Dave Kearney.
Now Ulster's Payne has been revealed to have suffered a hamstring problem, leaving his chances of facing England in serious doubt.
Payne will not train at all with Ireland this week, leaving him facing a race against time to take on the English.
Ulster duo Stuart McCloskey and Luke Marshall would likely compete for a starting berth should Payne fail to recover in time for the Twickenham clash.
Leinster's young centre Garry Ringrose could come into the wider equation of joining the Ireland squad as further cover. But Schmidt would have to take a bold step to draft the 21-year-old into the senior squad for the first time ahead of what will no doubt be a bruising battle with England next weekend.
"Jared Payne has got a grade one hamstring strain that he actually did in the first-half against France," said Schmidt.
"Jared said he would go as long as he could, and he was doing a good job for us defensively.
"He certainly won't train this week and we'll have to monitor him in the lead-up to the England game."
Ireland will certainly be without Sean O'Brien for the England clash, with the extent of his latest hamstring problem still being assessed.
Kearney is expected to miss out with his shoulder problem, while Cian Healy and Mike Ross will continue their injury returns by featuring for Leinster again this weekend.
Healy continues to step up his recovery from knee surgery, while Ross is easing past hamstring trouble. Both could yet return to Test action against England, in what would prove a vital boost to Ireland's creaking scrum.
"Cian Healy and Mike Ross got through a bit of time for Leinster last weekend and they will spend some time with us this week before going back to play for Leinster at the weekend," said Schmidt.