FIFA has dubbed Morocco's decision to play Nordin Amrabat against Portugal as 'questionable', following the concussion sustained in the defeat to Iran.
Amrabat was forced off during Morocco's Group B defeat to Iran on Friday following a clash of heads, which led to the Watford midfielder sustaining memory loss and spending the night in hospital.
FIFA guidelines suggest a minimum of six days on the sidelines after concussion but do not have authority to enforce their ruling, with the final decision resting with the team doctors.
While Amrabat started the game against Portugal wearing a protective cap, the 31-year-old discarded it after just a few minutes and his selection attracted widespread criticism.
"Following the questionable handling of the concussion incident involving the Moroccan player, [Nordin] Amrabat, during the Morocco-Iran match, FIFA wrote to the Moroccan team doctor to remind him of the importance to adhere to the guidelines that have been communicated," FIFA said in a statement.
"While the assessment and case management of concussion incidents falls under the sole responsibility of the respective team doctors, FIFA will address this matter with the Moroccan FA and, speaking in general terms, FIFA will monitor closely this matter throughout the competition."
FIFA added that the Moroccan Football Federation would need to explain why Amrabat was allowed to play against Portugal, while FIFPro, the world players' union, condemned Amrabat's involvement in their own statement.
"This is yet another alarming example of a player being put in harm's way. Amrabat returned to action too soon according to medical guidelines," they said on Twitter.
"Four years on from the debacle of the last World Cup, where several players did not receive adequate care, football has not made sufficient progress in concussion management. Calls to implement world-class standards have been overlooked."