Racing Metro have confirmed that Ireland international outhalf Johnny Sexton has suffered four concussions this year and as a result must serve a 12-week stand-down period.
The medical ban means that Sexton is unavailable to play rugby again until 14 February, the same day that Ireland play France in their second 2015 RBS 6 Nations clash.
If the ban stands, he will sit out all rugby until that point, including Ireland's Six Nations opener against Italy on 7 February.
The ban comes as a result of the the concussion protocol put in place by World Rugby and the LNR (Ligue Nationale de Rugby); the protocol states that after suffering four instances of concussion in a year, a player must observe an obligatory stand-down period of 12 weeks.
“It is most unfortunate and I feel bad for the club,” Sexton told racing-metro92.com. “ But I’m still not feeling 100%, and with injuries like this it’s not worth taking any risks.”
"I’m still not feeling 100%, and with injuries like this it’s not worth taking any risks” - Johnny Sexton
After recently beating both South Africa and Australia, Sexton must now await a check-up with two independent neurologists on 7 February before he can resume full contact training.
“It’s always difficult when you are deprived of a player of Johnny’s class,” admitted Racing coach Laurent Labit. "But we have deep respect for the players' health. His health is more important than whether we win or lose. We just hope that he will come back fully fit to end the season on a high for the Ciel et Blanc.”
Sexton added: “Today I’m feeling very disappointed for the club and my team-mates that I won’t be able to contribute to the team for such a long period.
“But I’ll make sure I come back better than ever, and hopefully make up for lost time when I’m fit to do so.”
Given that the earliest Sexton could return to contact training would be 8 February, it seems highly unlikely that he will feature for Ireland against France due to his lack of game time, thus making Ireland's home clash with England on 1 March the earliest date that he is likely to be seen in green again.