A leading brain injury charity has questioned whether protocols were followed after Manchester United defender Harry Maguire suffered a blow to the head in the opening minute of his side's Premier League victory at Fulham on Saturday.

Maguire went down on his haunches and looked uncomfortable after being caught on the side of the head by Rodrigo Muniz's shoulder during a challenge at Craven Cottage.

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He was checked on the pitch for possible concussion by United's team doctor -- as per Premier League guidelines -- but allowed to continue, although the England international needed a second check after half time.

The incident again raised the issue of "temporary concussion substitutes" being introduced, whereby a team could bring on a replacement while the injured player is assessed off the pitch, as they have already in rugby.

"We have come such a long way since Hugo Lloris was labelled a 'hero' for over-ruling club medics to return to the pitch after a clear concussion while playing for Tottenham against Everton in 2013," Luke Griggs, Chief Executive of Headway, said in a statement.

"That shocking incident was a wake-up call for football. We called it 'dangerous and irresponsible' at the time, demanding it be used as a catalyst for change.

"But this progress is eroded with every high-profile incident in which the safety first principle is set aside and players being allowed to continue despite showing signs that a concussion could have occurred."

There is no suggestion that Manchester United's medical staff did anything wrong, but Griggs said the incident highlighted again the need for concussion substitutes to be adopted across the sport.

"This is an issue with the very culture of football and its stubborn refusal to put players' health above all else -- including the result of a game," he said.

"Temporary concussion substitutions would immediately help return some credibility to the process, but an evolution of attitude is urgently needed."

Maguire said he had passed the concussion tests on the pitch.

"The doc did all the tests and I knew where I was and I was answering all the questions and I completed them, [the concussion protocols] thankfully," he said.

"If the doc says I'm okay to carry on, then I'm always going to carry on."

Earlier this year, the International Football Association Board (IFAB) rejected a trial for temporary concussion substitutes in the Premier League, Ligue 1 and MLS.

World governing body FIFA is continuing indefinitely its trials for permanent substitutions -- whereby a team can have an extra substitute in the case of a player being withdrawn because of a likely concussion.