Johnny Sexton is feeling the heat from France to be stood down from Sunday's Six Nations clash.

The French neurologist that ordered Sexton to take 12 weeks off in 2014 during his stint with Racing has claimed that the 35-year-old has had 30 concussions in his career.

Sexton was withdrawn in the championship opener against last weekend after his head collided with Justin Tipuric's knee in the 69th minute, and underwent a HIA after the game.

"The doctor's part, fundamental to this story, is...if there are symptoms, if his tests are disturbed, the doctor must stop him from playing on Sunday," Dr Jean-François Chermann told RMC Sport.

"Conversely, if there are no symptoms, if the tests are perfect, the fact that he has had many concussions before is a problem, but I think we do not have enough obvious elements to prevent him from continuing his rugby career.

"Listen, I think Johnny Sexton has had around 30 concussions across his entire career.

“It’s true that it’s enormous. But when he was playing for Racing he showed exceptional cognitive performance.

"So what is needed is that he knows what he is incurring to make the right decisions."

Ireland defence coach Simon Easterby confirmed yesterday that the plan was for Sexton and James Ryan, who failed to return from a 23rd minute HIA, to play against Les Bleus.

Ireland's Cian Healy and Julien Marchand of France compete for possession

French star Julien Marchand came off for a HIA in his side's opening 50-10 win against Italy but subsequently returned to the action in Rome.

Marchand was asked yesterday if it sent out the wrong message for Sexton to play after he was in discomfort after suffering the injury.

"Of course it's not a good thing if someone is concussed, that he was knocked out and took several blows to the head," said the hooker.

"We're beginning to learn a little about the damage that can happen later in one's life. After all that, though, nobody else can speak for him.

"We do not know what he has exactly. Maybe he just took a blow to the head and everything is fine.

"This whole procedure is a delicate matter.

"Personally if I had been knocked out or taken a heavy blow to the head I would give up my place for the game.

"But it's not for me to answer in the place of someone else. He (Sexton) will reply to everybody and we'll see this weekend."

Meanwhile, Easterby defended Billy Burns after his late kicking error stopped Ireland from having one last shot at winning in Cardiff.

Ireland assistant coach Simon Easterby

Burns was upset with himself afterwards for missing his penalty kick to the corner but Easterby said: "I think it's incredibly tough when you feel like that is the moment that might have not given you the opportunity to win the game.

"But for me, it's a mistake. You can look back at the game and there are plenty of opportunities for us to have won that game.

"Yes, it was a critical moment and yes, we have to be better at winning those critical moments and making sure we're accurate.

"But we conceded two tries which I feel we should have avoided. We conceded penalties, which again were definitely avoidable, and to put something like the winning or losing of a game onto that one moment is wrong.

"I believe that he is massively upset about the situation and his lack of accuracy in nailing the kick.

"We would certainly want him to try and get to the five (metre line) if he can, because it makes such a difference to the quality and the effectiveness of that maul or the play that is off that, so certainly we want him to have the confidence to go for that if that situation happened again.

"But for me, there was plenty of other opportunities and moments in the game for us to win it, rather than singling out that one."