Ireland second row James Ryan will miss their final Six Nations match against Scotland on Saturday as he goes through return to play protocols after suffering a concussion in last weekend's 32-15 victory over England.
The Leinster lock left the pitch at Twickenham after less than two minutes following a head-on-head tackle by Charlie Ewels that led to the England second row's dismissal.
Ryan Baird, who started in place of Ryan in the previous outing against Italy, has also been ruled out with a back issue. Ulster's Iain Henderson is likely to join Tadhg Beirne in the second row, having come on for most of the game on Saturday.
Ireland had already lost two first choice front row players to injury earlier in the competition and their scrum struggled mightily against England's makeshift pack without prop Andrew Porter and hooker Ronan Kelleher.
Ireland trail France by two points and are the only team who can stop the unbeaten leaders from winning the title. They will almost certainly need England to win in Paris on Saturday to have a shot at the championship by beating Scotland in Dublin.