England full-back Mike Brown has been ruled out of Sunday's Six Nations match against Ireland as he struggles to recover from a bout of concussion, the Rugby Football Union announced on Wednesday.
Brown suffered the injury in a clash of heads during the 47-17 win over Italy at Twickenham earlier this month.
"Mike and our medical staff have been diligent during every step of the graduated return to play protocol and they will continue to work to get him back to full health," said England head coach Stuart Lancaster, who is set to replace Brown with Alex Goode.
England assistant coach Andy Farrell revealed that Brown woke up with a mild headache after completing Tuesday's running session.
"This morning Mike woke up not feeling 100 percent. The right and proper thing to do was to make the call. His health is the main priority here and we need to get him right for the next game," Farrell said.
Of the decision to replace Brown with Goode, Farrell added: "Mike has been in great form. He's a guy who stands up in pressure situations and performs extremely well. With the young back line we have, he's been a massive help for us.
"But Alex is an experienced guy himself who has been waiting for his chance for some time now. His form for Saracens in the big games against Munster and Clermont and in recent matches has been exceptional."
England and Ireland, who will meet in Dublin, are the only sides left in the Six Nations with 100 percent records.
Source: AFP