Benjamin Pavard revealed he was knocked out for "10 to 15 seconds" before returning to the field in France's 1-0 win over Germany at Euro 2020.
Pavard sustained a head injury following a collision with Germany's Robin Gosens as world champions France opened their Group F campaign with victory on Tuesday.
France defender Pavard was left on the floor before receiving treatment for several minutes in Munich, where he was eventually allowed to continue.
"I took a hell of a shock," Pavard told beIN Sports post-match.
"I was a little knocked out for 10 to 15 seconds. After that, it was better."
A "concussion charter" was signed by all 24 teams at Euro 2020 – a commitment to taking a series of measures to improve the care of players and includes neurological baseline testing and access to in-match television replays for team doctors.
But the incident involving Pavard has raised further questions about concussion protocols in football.
FIFPro has long called for temporary concussion substitutions and the enforcement of a minimum six-day gradual return to play.
"The issue of concussion is a very serious issue. It's a health and safety issue, which is related to their work place. In my point of view, I don't think it's been addressed in the proper manner it should be addressed," FIFPro vice-president Francis Awaritefe previously told Stats Perform.
"We've seen the medical data around the long-term risks of concussion and how they can have a deleterious long-term effect for people who suffer concussion when it's not managed properly.
"We're really worried about it because football seems to be a long way behind some of the other sports in terms of protocols and just in terms of the way how seriously they're taking concussion.
"For me, it's a massive issue. We don't want to wait until a player has a serious injury that it might end their career or worse, we have a player die on the field or soon after because of a concussion issue that wasn't treated properly.
"As a sport, we need to reflect on this and get together with experts to come up with smart and proactive solutions to deal with this really, really serious issue."
Brendan Schwab – executive director of the World Players Association – also told Stats Perform previously: "When concussed, it's not the time for the player to make a decision as to whether they should continue in a game. That is a decision that needs to be placed in the hands of independent medical assessors who have no duty other than to act in the best interests of the player.
"There needs to be independent medical assessors on the sidelines. But we do expect this to be resisted because it is resisted in other sports. We now have independent medical assessors on the sidelines of the NFL and it's only because the NFLPA fought for that right. It was a battle.
"Now the suggestion that the club doctor knows the player better than another doctor, again, is not a medically-based comment. What we do know, however, is that the club doctor who is employed by the club has a conflict of interest. That conflict of interest needs to be minimised and voided in circumstances when dealing with head injuries.
"If FIFA doesn't change, what we will see is football leagues at the national level collectively bargain their own variation of the laws of the game. In Australia, the knowledge is clear that the clubs as employers would be in breach of health and safety requirements, and acting against the wishes of the unions, by putting players back into the game when they're clearly in a vulnerable position. What's to prevail there? Laws of the game or national health and safety laws? National health and safety laws have to prevail. It won't be a defence to any action for an employer to say 'we were simply providing an unsafe work practice at the behest of FIFA'."