England boss Stuart Lancaster waits on Mike Brown ahead of Lansdowne showdown

Mike Brown is still suffering concussion symptoms and faces a race against time to prove his fitness for England’s pivotal RBS 6 Nations clash against Ireland in Dublin.

Saracens playmaker Alex Goode is the front-runner to replace Brown should the 29-year-old fail to beat the concussion he suffered in Saturday’s 47-17 victory over Italy. Exeter’s versatile Nowell could replace May.

“We’re going to have to see how Mike Brown comes through the return to play protocols,” said England boss Stuart Lancaster.

Lancaster could parachute in Exeter wing Jack Nowell to replace Johnny May, with Brown’s concussion symptoms threatening a changed back-three for the potential title decider on March 1.

Confirming Nowell is back in his selection thoughts, Lancaster claimed May is not automatically jettisoned despite a shaky showing against Italy.

“It’s early days yet. We are keeping our options open.

“Ireland’s half-backs are excellent: Sexton showed his quality and class against France at the weekend, not to play for 12 weeks and then come back and play so well. His and Conor Murray’s kicking games are both excellent.

"As a consequence, you have to be absolutely on your game in your back-field coverage because they will try to exploit any weaknesses in your armoury.”

Meanwhile Scotland have been hit with a fresh injury blow after lock Richie Gray was told his Six Nations is over. The Castres forward suffered an upper arm injury in Sunday’s 26-23 defeat to Wales at Murrayfield and is out for 12 weeks.

Elsewhere Cardiff flanker Rory Watts-Jones has been forced to retire on medical grounds. He suffered a concussion-related injury in November and his exit comes in the wake of high-profile head injuries to Wales pair George North and Samson Lee.